


TRIUMPHS AND WONDERS OF 
MODERN CHEMISTRY 



TRIUMPHS & WONDERS 

OF 

MODERN CHEMISTRY 



A Popular Treatise on 

Modern Chemistry and its Marvels, written in 

Non-Technical Language for General 

Readers and Students 



BY 

GEOFFREY MARTIN, D.Sc, Ph.D. 

FIRST-CLASS HONOURSMAN IN CHEMISTRY OF LONDON UNIVERSITY 

AUTHOR OF " TRIUMPHS AND WONDERS OF MODERN CHEMISTRY," " PRACTICAL 

CHEMISTRY," "INDUSTRIAL CHEMISTRY," "THE HALOGENS," "CHEMICAL 

LECTURE DIAGRAMS," " RESEARCHES ON THE AFFINITIES OF THE 

ELEMENTS," ETC., ETC. 



ILLUSTRATED 




NEW YORK 
D. VAN NOSTRAND COMPANY 

TWENTY-FIVE PARK PLACE 
1919 



L 









aft 









Dedication 



TO 

MY DEAR MOTHER 

THIS BOOK IS DEDICATED 



PREFACE 

Within the last few years Chemistry has been revolutionised 
by startling discoveries which have followed one another 
in quick succession, and these are briefly described in the 
following pages. The atoms have been shown to be of im- 
mense complexity, the seat of vast forces and terrific motions, 
the very existence of which was, scarce dreamt of until the 
advent of radium. A series of magnificent researches has 
recently shown us that these atoms, far from being the 
changeless and eternal foundation stones of the Universe 
that they were once thought to be, are themselves crumbling 
away. Such conceptions and discoveries have altered the 
whole aspect of chemistry, and have necessitated the treating 
afresh of many old problems previously regarded as settled. 
It has been my lot while lecturing on Chemistry to have 
come into frequent contact with many thoughtful men and 
women, boys and girls, who have felt much interest in this new 
chemistry, which has arisen out of the old, and who have 
wished to know something more of the grand questions of the 
day touching the ultimate nature and constitution of the Uni- 
verse in which they live, and of the matter which surrounds 
them on every side in untold millions of tons, but who have 
neither the leisure nor the inclination to master the tech- 
nicalities and enter into the minutiae of the regular text- 
books of Chemistry where such things are discussed. These 
text-books, moreover, labour under the disadvantage that 
they are written for candidates studying for one or other 
of the innumerable examinations in which our University 
authorities take such a keen delight, and which, combined 
with a complete lack of educational freedom, make an Eng- 
lish University Student's life a perfect nightmare to him 
(in sad contrast to that of a German or American Student), 

vii 



viii PREFACE 

and destroy rapidly and effectively any genuine interest in 
Science that he may have possessed at his entrance to the 
University, besides exercising a paralysing effect on the Uni- 
versity Lecturers themselves, and diminishing greatly the 
output of research work in this country, to its incalculable 
material and moral harm. 

This book is not written for examination candidates. It 
is written in order to awaken the interest of the general 
reader and the young student in what is after all a grand 
science ; for Chemistry is the Science which tells us that 
Nature works by unseen bodies — by myriads of tiny atoms 
whirling in gigantically swift and infinitely complex motion, 
the whole forming a microcosmic world beneath the visible 
world — and that her true laboratory consists of " events in 
inconceivable numbers, the whole phantasmagoria of these 
events changing every instant down to its minutest details 
with inconceivable rapidity.'' The most insignificant objects 
are fraught with endless wonder and mystery. A breath of 
wind is the swift rush of millions of atoms, the blazing of a 
match the destruction of a universe almost infinite in com- 
plexity and the building up of a new one out of its ruins, while 
in the tiniest grain of dust dancing in a sunbeam the rush of 
atomic events in the millionth part of a second is so incredibly 
swift as to defy all conception and calculation. Indeed, the 
whole universe, from its uttermost heights to its deepest 
depths, is but one vast system in a state of ceaseless and stu- 
pendous chemical change., This book represents an effort to 
give the general reader a picture of the world in which the 
chemist wanders, and an idea of the great and wonderful 
problems with which modern chemistry deals. At the same 
time it is hoped that the book will prove useful both to 
popular lecturers and to Chemistry teachers in need of 
interesting illustrative facts for their routine chemical classes. 

Every care has been taken to keep the subject matter as 
thoroughly up-to-date as possible. In every case the most 
recent authorities, not only English but foreign as well, 
have been consulted, and references are given to much of the 
original literature for those who wish to pursue the subject 
further. No one authority has been slavishly followed, but 



PREFACE ix 

an endeavour has been made to put every fact in a fresh and 
original way. Indeed, the reader will find several new views 
published here for the first time, while many old problems 
have been presented in a novel form and treated on lines 
different from those usually adopted in the ordinary chemical 
text-book. Part of my object has been to break away 
from the stereotyped text-book style, without thereby 
sacrificing scientific exactitude and precision. By such 
means I hope to bring the reader into immediate contact with 
the thoughts of the great leaders of science, whose ideas, 
usually buried away in the transactions of learned societies, 
are inaccessible to all but the specialist. 

My searchings in the original memoirs and addresses of 
the great leaders of chemical thought have been very exten- 
sive, and represent a labour extending over some years. If, 
however, I succeed in awakening the interest of the intelligent 
reader in our science, such labour will not have been in vain. 

On every doubtful point I have not hesitated to consult 
with leading authorities who have made a special study of 
the subject, and so I hope that few errors will have crept into 
the following pages, and that the views presented will be in 
accordance with the most recent results of scientific research. 

My best thanks are due to Dr. Henry J. S. Sand, Ph.D., 
D.Sc, whose deep and exhaustive knowledge of the most diffi- 
cult developments of Modern Chemical Science was ungrud- 
gingly placed at my disposal in writing this book. Almost 
every page has been benefited by his criticism and advice. 

I am much indebted to Sir William Crookes, F.R.S., for 
his kindness in revising the chapter on Nitrogen and our 
Food Supply, to which he appended some observations and 
corrections, which are all the more valuable since they come 
from the eminent chemist who first called the attention of 
the scientific world to this great problem in his famous 
address to the British Association. 

To Mr. Frederick Soddy, M.A., I am indebted for informa- 
tion and corrections on the radio-active elements — a subject 
on which his researches have become classical. To Dr. 
Caven, D.Sc, F.I.C., I am indebted for some manuscript 
notes, which have enabled me to treat some portions of the 



x PREFACE 

subject in an original manner. Mr. Golding, F.I.C., of the 
Midland Agricultural College, Kingston, Derby, was kind 
enough to allow me to reproduce photographs illustrating 
his experiments on " Nitrogen-fixing " organisms ; I have 
also to thank him for advice and information on this subject. 

My best thanks are due to Mr. Prichard, of the Notting- 
ham Library, for the trouble he took in looking up books 
and records for certain information ; also to my wife for 
many suggestions, useful criticism, and active help. 

Among other authorities with whom I have had occasion 
to correspond while preparing this book may be mentioned : 
Miss Ida Freund, of Girton College, Cambridge, who gave 
me some information regarding Lucretius' Poem " De Rerum 
Natura" ; Mr. W. C. D. Whetham, M.A., F.R.S., who gave 
me leave to use part of his book, " Recent Developments 
of Physical Science " ; Mr. Edwin W. Streeter, who allowed 
me to quote from his work on " Precious Stones " ; Mr. J. E. 
Gore, F.R.S., who revised some of the astronomical state- 
ments made in the early parts of the work, and who gave me 
permission to quote from some of his works on Modern 
Astronomy ; Mr. Kipling, who gave me leave to quote 
from his poem " Sea-Cables " ; Sir William Ramsay, F.R.S., 
who corrected some statements regarding his researches; 
Mr. Edw. A. Oates, British Vice-Consul at Porto Empedocle, 
Sicily, who procured for me illustrations of the Sulphur 
District, Girgenti, Sicily ; Bryant & May, who gave me infor- 
mation on Match Manufacture; Siebe, Gorman & Co., who 
gave me information and illustrations regarding their oxygen 
apparatus. Among the firms who have allowed me to quote 
from some of their publications may be mentioned : Kegan 
Paul, Trench, Triibner & Co. ; The Cambridge University 
Press ; Macmillan & Co. ; The Proprietors of Cassier's 
Magazine ; Harper Brothers ; Seeley & Co. ; Grant Richards ; 
Methuen & Co.; John Murray; Smith, Elder & Co. ; The 
English Illustrated Magazine ; The Strand Magazine ; The 
Forum. To all of these I return my best thanks. 

Geoffrey Martin. 
Birkbeck College, 

University of London. 



CONTENTS 

CHAPTER I 

THE MYSTERY OF MATTER 

PAGE 

Eternal Circulation of Matter in the Universe — Indestruc- 
tibleness of Matter — Theories of Matter — The Ether — 
Osborne Reynolds' Theory of Matter — Electronic Theory 
of Matter — Is Matter really Indestructible ? — Nature 
of Mass — Amount of Matter in the Universe i 

CHAPTER II 

THE UNDERWORLD OF ATOMS 

The Universe in a State of Flux — Atomic Theory of the 
Greeks — Lucretius' Poem, " De Rerum Natura " — 
Newton's Views on Atoms — Dalton's Atomic Theory 
— Avogadro's Work — Molecules — Magnitude of Mole- 
cules — Molecular Science and Living Matter — Molecular 
Speeds — Vast Speeds prevailing within the Molecules — 
Possibility of seeing Molecular Motion — The Ultra- 
microscope and its Wonders — The Shapes of Atoms — 
Pasteur, Le Bel, and van't Hoff's Work — Optical 
Activity .......... n 



CHAPTER III 

DISTRIBUTION AND EVOLUTION OF THE ELEMENTS 

What is an Element ? — What the World is made of — Dis- 
tribution of the Elements in Space — What Meteorites 
teach us — Cosmical Dust — The Interior of the Earth 
probably Metallic Iron — The Crust of the Earth — Un- 
equal Distribution of the Elements probably due to 
Evolution — How the Elements came into Being — 
Thomson's Electronic Theory — The Proto-Elements — 
Will the light Elements all turn into heavy ones ? — The 
World's Future — Stellar Evidence for the Evolution of 

xi 



xii CONTENTS 

PAG* 

the Elements — Lockyer's Work — Arrhenius' Views — The 
Laboratories of the Universe — Vastness of Nebulas — 
Chemical Changes going on in Nebulae and Stars — 
Enormous Temperatures and Pressures prevailing in 
the Depths of the Sun and Stars — Gigantic forces 
prevailing in their Depths — Probable Formation and 
Decomposition of Elements in Stars and Nebulas — 
Human Chemistry necessarily of very limited Scope — 
The Disintegration of the Elements — Radium — Energy 
residing within Matter Atoms — The Universe Eternal 
— Arrhenius' Views — Herbert Spencer's Views . . 31 



CHAPTER IV 

THE WONDERS OF CHEMICAL CHANGE 

The Wonders of Chemical Combination — Chemical Forces 
probably electrical in Origin — Vast Magnitude of Chemi- 
cal Forces — Why Atoms when they unite cause the 
Evolution of Heat and Light — Swiftness of Atomic 
Events — Johnstone Stoney's Views on Molecular Collision 
— Chemical Forces Supreme in the Universe — Chemical 
Symbols and Equations — A Chemical Change a Molecular 
Catastrophe — Structure of Molecules — Fournier d'Albe's 
Speculations • 55 

CHAPTER V 

WATER 

Antiquity of the Ocean — Origin of the Ocean — Early Con- 
dition of the Earth — Water exists in Neighbouring 
Planets — The Ocean sinking into the Crust of the Earth — 
Future Fate of the Ocean — Water inJLiving Matter — 
Circulation of Water over the Earth — Water evolved 
by Vegetation — Chemical Composition of Water — How 
Water freezes — Influence on the World — Ice — Gaseous 
Water — How Water boils — Effect of Temperature on the 
Properties of Water 82 

CHAPTER VI 

THE ELEMENT HYDROGEN 

Early History of Hydrogen — Preparation — Explosions in 
Iron Smelting due to Hydrogen — Explosion of a War- 
ship's Boiler due to Hydrogen — Hydrogen and the 



CONTENTS xiii 



PAGB 



Evolution of the Elements — Prout's Hypothesis — 
Hydrogen in Space — Vast Hydrogen Flames on the Sun 
— Hydrogen on Stars — Hydrogen and Exploding Worlds 
— Hydrogen in Water — Hydrogen in the Air — Balloons — 
Glaisher's and Coxwell's Ascents — Tragedies of the Air — 
Properties of Hydrogen — Liquid Hydrogen — Dewar's 
Researches — Structure of Hydrogen Gas — Hydrogen 
Atoms enormously complicated Structures . . . 107 



CHAPTER VII 

THE AIR 

The Mystery of the Air — Properties of Air — Why Air is 
invisible — How the Air protects us from the Awful Cold 
of Space — How it protects us from Meteorites — Height 
of the Atmosphere — Circulation of the Atmosphere — The 
Aurora Borealis — Composition of the Air — Aqueous 
Vapour in the Air — Clouds — Carbon Dioxide and Ozone 
in the Air — The Upper Regions of the Atmosphere consist 
of Hydrogen and Helium — Dust in the Air — The Won- 
ders of Dust — Cosmic Dust — Molecular Structure of 
Air — Liquid Air and its Wonders — Solid Air — Action of 
Great Cold on Living Matter — Bacteria are not killed by 
Intense Cold — Arrhenius' Theory of the Spread of Life 
in the Universe by Means of Radiation Pressure — Past 
and Future Changes in the Composition of the Atmo- 
sphere — How Oxygen got into the Atmosphere — Ultimate 
Fate of the Atmosphere — The Atmospheres of other 
Worlds — Johnstone Stoney's Theory of Planetary 
Atmospheres — Atmosphere absent from the Moon — At- 
mosphere of Venus — Atmosphere of Mars — Atmospheres 
of Jupiter, Saturn and Neptune — The Sun's Giant 
Atmosphere 126 



CHAPTER VIII 

OXYGEN, THE LIFE-SUPPORTING ELEMENT 

All Living Matter ceaselessly combining with Oxygen — How 
Oxygen combines with the Blood — Nature of Haemo- 
globin — Oxygen essential to Animal Life — Effects of 
withdrawing the Oxygen from the Air — Astonishing 
Properties of Oxygen — Life in an Atmosphere of Pure 
Oxygen — Liquid Oxygen — Molecular Structure of Oxygen 
— Uses of Oxygen — How Oxygen has saved Lives in 
Exploded Mines — The Courrieres Disaster — The Ham- 



xiv CONTENTS 



PAGE 



stead Disaster — How Mr. Fleuss saved the Severn 
Tunnel by means of Oxygen — Oxygen for Athletes — 
Reviving Power of Oxygen — Preparation of Oxygen 
from Potassium Chlorate — The largest Preparation of 
Oxygen on Record — Manufacture of Oxygen from the 
Air by Linde's New Process — Vast Mass of Oxygen in 
Nature — Oxygen in the Crust of the Earth — Ozone — 
Explosive Properties of Ozone — Energy in Ozone — 
Ozone as a Cosmical Agent for trapping Energy — An 
Ozone Planet 165 



CHAPTER IX 

THE ELEMENT NITROGEN 

Chemical Inertness of Nitrogen — Preparation of Nitrogen — 
Properties of Nitrogen — Life on a Nitrogen World — 
Energies locked up in Nitrogen — How Lightning com- 
bines Nitrogen — Nitrogen in Living Matter — Nitrogen 
chemically combined in the Soil essential for Fertility — 
Our Food Stuffs depend upon the Nitrogen fixed in the 
Earth — Exhaustion of Nitrogen in Cultivated Lands — 
Manures — Sodium Nitrate or Chili Saltpetre — Approach- 
ing Exhaustion of the Saltpetre Beds — Problem of 
Fixing Atmospheric Nitrogen — Crooke's Work — Nitrify- 
ing Organisms — Nobbe and Hiltner's Nitragin — Birke- 
land and Eyde's Nitrogen-fixing Factory at Notodden 
in Norway — Professor Franke's Method of Fixing 
Atmospheric Nitrogen — Nitrolime — Cyanamide — Artifi- 
cial Urea and Guanidine — Artificial Creatine — Will 
our Food be made in the Future in Chemical Laboratories? 
— Circulation of Nitrogen in Nature . . . • i8q 



CHAPTER X 

THE ELEMENT CARBON 

Power used in Modern Civilisation depends upon Carbon — 
Amount of Carbon in the Rocks — In Coal — In the Sun 
and Stellar Regions — Carbon in Living Matter — Dia- 
monds^ — Infusibility of Carbon — How Carbon can be 
Melted — Artificial Diamonds — Moissan's Work — Origin 
of Diamonds — How the South African Diamond Mines 
were discovered — Description of the Kimberley Mines 
— Strange Life History of the Diamond — How Diamonds 
burst — Diamonds and Coal identical — How Diamonds 
burn — The Story of some Wonderful Diamonds — 



CONTENTS xv 

PAGB 

Graphite — Where Graphite is found — How Graphite is 
manufactured — Charcoal and its Wonderful Structure — 
Coal and its Wonderful Story — Kingsley's Description 
of a Coal Forest — General Properties of Carbon — Its 
Chemical Affinities — Astonishing complexity of Carbon 
Compounds — Cellulose, the Skeleton of Vegetable Life — 
The Sugars — Albumen — Camphor — Indigo and other 
Dyes — Wonders of the Atomic Structure of Carbon 
Compounds 206 



CHAPTER XI 

CARBON DIOXIDE 

How Coal burns to an Invisible Gas called Carbon Dioxide — 
How to prepare Carbon Dioxide — Its curious Properties — 
Dangers of Carbon Dioxide — Evolution of Carbon Dioxide 
from the Earth— The Death Valley of Java— The Death 
Gulch of America — Carbon Dioxide Fountains around 
the Laacher Sea — The Grotto del Cane — Evolution of 
Carbon Dioxide from Vesuvius and Volcanoes — Evolution 
of Carbon Dioxide from the Earth in Past Ages — The 
Volcanic Eruption in Iceland in 1783 — Suffocation of the 
Elder Pliny by Carbon Dioxide evolved from Vesuvius — 
Evolution of Carbon Dioxide from Garden Land — 
Accumulation of Carbon Dioxide in Old Wells and Vaults 
— Evolution of Carbon Dioxide from Living Creatures — 
From burning Coal — From Volcanoes — Absorption of 
Carbon Dioxide by the Rocks in the Process of Weather- 
ing — Vast Amounts of Carbon Dioxide chemically com- 
bined in Limestone and Chalk — Absorption of Carbon 
Dioxide by Plants and its Decomposition into Oxygen 
by their Agency — Vast Amounts of Energy poured forth 
from the Sun into Space — Plants a Means of Fixing Part 
of this Energy — Circulation of Carbon in Nature — Carbon 
Dioxide steadily accumulating in the Atmosphere — The 
Climate must improve in consequence — Changes in the 
Earth's climate in Geological Times probably due to 
varying amounts of Carbon Dioxide in the Air — Much 
Carbon Dioxide in Air produces a warm Climate and a 
Luxurious Vegetation — Solubility of Limestone in Water 
containing Carbon Dioxide in Solution — Hard and Soft 
Water — Wonderful Limestone Caverns — The Limestone 
Caves of Carniola — Dr. Schmidl's Explorations of Under- J 
ground Caverns — The Cave of Caripe in Venezuela — 
Grotto of Adelsburg — The Mammoth Cave — Lake of 
Zirknitz — Earthquakes due to the Collapse of Under- 
ground Caverns — Stalactites and Stalagmites . . 214 



xvi CONTENTS 

CHAPTER XII 

SILICON AND ITS COMPOUNDS 

PAGE 

Silicon in the Earth's Crust — Silica — Sand and Sandstone — 
Quartz — Flint — Opals — Rock Crystal — Discovery of 
Rock Crystal Caves in the Galenstock — Silica Glass 
and its wonderful Properties — Quartz Fibres — Solubility 
of Silica in Water — Geysers and their Siliceous Deposits — 
Silica Terraces in Volcanic Regions — Silicic Acid — 
Secretion of Silica by certain Organisms — Constitution of 
the Earth's Crust — Silicates — Wonderful Structure of 
Rocks — Weathering of Rocks — Chemical Changes that 
the Earth's Surface is Undergoing — How Clay and Sand 
are formed — Glass — Antiquity of Glass Manufacture — 
Pottery . 265 



CHAPTER XIII 

SULPHUR AND ITS COMPOUNDS 

How Sulphur is formed in the Earth — Uses of Sulphur — 
Wonderful Sulphur Mines of Sicily — A Sulphur Mine 
on Fire — -Sulphur in Japan — Mountains of Sulphur in the 
Island of Etrofu — Formation of Sulphur in Craters of 
Volcanoes — Sulphur Deposits in Java — Wonderful Sulphur 
Caves — How Montano obtained Sulphur for Cortes from 
the Crater of Popocatapetl — Probable Existence of 
Sulphur Deposits on the Moon — Description of the 
Sulphur Deposits in the Crater of Vesuvius — Sulphur 
Bacteria — Sulphur in Living Matter — Sulphides — Pro- 
perties of Sulphur — Sulphuretted Hydrogen and its 
Dangers — Accidents to Workmen through Sulphuretted 
Hydrogen in Drains — Evolution of Hydrogen Sulphide 
from the Ground during the Building of Smith's Point 
Lighthouse — Sulphur Dioxide — How Pliny Died from 
Poisonous Gases containing Sulphur Dioxide — Sulphuric 
Acid 291 



CHAPTER XIV 

THE PHOSPHORUS GROUP OF ELEMENTS 

Discovery of Phosphorus by Brandt — Wonderful Properties 
of Phosphorus — Manufacture of Phosphorus in the 
Electric Furnace — Use of Phosphorus for Matches — 
Dangers of Phosphorus — Phossy Jaw — Poisoning by 



CONTENTS xvii 

PAGE 

Phosphorus — Red Phosphorus — Safety Matches — How 
Matches are Made — Phosphorus in Living Matter — Phos- 
phorus Manures — Phosphates — The Tale of a Phosphorus 
Atom 308 



CHAPTER XV 

FIRE, FLAME, AND SPECTRAL ANALYSIS 

Nature of Fire — Combustion — Structure of Flame — The 
Bunsen Flame — The Incandescent Mantle — Neglect of 
Research — Wonders in a Candle Flame— Chemical 
Analysis of distant Suns — Principles of Spectrum 
Analysis— Wonders of Spectrum Analysis . " . . 324 



LIST OF ILLUSTRATIONS 



LINE DRAWINGS IN THE TEXT 

Experiment illustrating the Indestructibility of Matter 

Use of the Ultra Microscope .... 

Shape of the Carbon Atom according to Modern Electron 

Theory 

Shape of Carbon Atom according to Wislicenus . 
Dissolved Crystals and their Plane of Polarisation 
Arrangement of Atoms in Molecule 
Predominance of Iron in the Earth 

The Solar System 

Sulphuric Acid Molecule ..... 
Reaction between PC1 6 and H 2 S0 4 — The Approach 
Reaction between PC1 5 and H 2 S0 4 — The Collision 
Reaction between PC1 5 and H 2 S0 4 — Formation of the 



cules POOL 



and S0 2 2 , as the result of 



Mole- 
the 



collision ....... 

Section of the Earth's Crust .... 

If Water became Incompressible .... 

Temperature of the Sea 

Snow Crystals . 

Production of Superheated Steam 

Preparation of Hydrogen 

Hydrogen Flames on the Sun's Surface 

Explosion of a Flask filled with Hydrogen and Oxygen 

Structure of Hydrogen Gas ..... 

Structure of Hydrogen Atom .... 

Section through the Earth's Atmosphere 

Linde's Apparatus for Liquefying Air 

Vacuum Jacketed Vessel for holding Liquid Air . 

Crystals of Oxyhemoglobin 

How the Severn Tunnel was Saved 

Preparation of Oxygen Gas from Potassium Chlorate 

Linde's Apparatus for separating Air into Oxygen 

Nitrogen 

Diagram Birkeland-Eyde Electric Furnace . 

Some Historic Diamonds 

The Benzene Ring 



and 



PAGE 

3 
23 

26 
27 
23 

29 
35 
7i 
73 

75 
76 



77 

87 

97 

99 

102 

103 

109 

113 
121 
123 
125 
135 
143 
145 
167 
176 
181 

181 
201 
220 
233 



xix. 



xx LIST OF ILLUSTRATIONS 

PAGB 

Framework of Carbon Atoms in Camphor .... 232 

Framework of Carbon Atoms in Indigo .... 232 

Framework of Carbon Atoms in Organic Dye . . . 232 

Dog Grotto near Naples 238 

The Bottomless Pit 257 

Echo River, Mammoth Cave . . . . . .258 

Exploration of Maelstrom in Mammoth Cave . . . 260 

Spear Head 270 

Spear Head *" 270 

Spear Head, Front and Profile 271 

Discovery of Rock Crystal Cave 274 

Euplectella Suberea Sponge 280 

Microscopic Structure of Siliceous Rocks .... 283 

Unburnt Gas in interior of Candle Flame . . . 325 

Cool Core in interior of Gas Flame 326 

Section of a Candle Flame 328 

Bunsen Burner 329 

Spectroscope 336 

Section of the Sun 338 

HALF-TONE PLATES, Etc. 
Silica Terraces at Rotomahana Frontispiece 

FACE PAGB 

Tripler's Apparatus for Experimenting with Liquid Air . 142 

Pouring Liquid Air . .146 

Kettle of Liquid Air on a Cake of Ice . . . .146 

Oxygen-breathing Apparatus 176 

Dr. Leonard Hill administering Oxygen . . . .178 

Nodule of a Bean Cut Open 196 

Nitrogen Assimilating Organisms in a Bean Nodule . . 196 

Vigorous Growth caused by Nitrogen Assimilating Organisms 196 

Nitrate Works at Notodden 198 

Lightning 198 

Birkland-Eyde Electric Furnaces 200 

Diamond Mines, Open Workings 212 

Searching Tables, Diamond Mines 216 

A Carboniferous Forest 226 

Stalactites 262 

Girgenti 294 

Sulphur Mountains, Japan 294 

In the Crater of Popocatapetl 298 

Lunar Landscape 300 

Vesuvius 306 

Gannets 316 

Plesiosaurus and Ichthyosaurus 318 

Nebula 338 

Spectra 338 



TRIUMPHS AND WONDERS OF 
MODERN CHEMISTRY 



CHAPTER I 

THE MYSTERY OF MATTER 

The endless circulation of matter in the universe is, perhaps, 
one of the most wonderful facts with which chemistry has 
to deal. It is this endless change which causes the history 
of the most common and insignificant objects about us to 
be more astonishing than any fairy tale. What a wonderful 
story, for example, could be written of the material which 
forms our bodies ! It came into existence in the immense 
depths of space millions upon millions of years ago, and 
wandered for ages through darkness and void until it 
reached our earth. Perhaps it fell upon the earth in a fiery 
meteorite, or perhaps it merely joined the huge fire mist 
from which our solid world condensed. Since then it has 
run round age after age in an endless circle of change. 
First it formed part of that vast primeval atmosphere which 
surrounded the globe, and blew in mighty winds around 
our planet ; then it was absorbed into the body of some 
humble living being, and when this being died and its body 
decayed, the matter passed into the rich mother earth. 
Thence it passed into some plant by means of its roots ; and 
from the plant it passed, by the process of being devoured, 
into the body of some animal ; and from the animal again 
it passed to earth and thence to plants and animals again ; 
and so on through an endless cycle of change, coursing 
through the bodies of innumerable multitudes of living 
forms, which stretch far back in a dim unending vista into 
the depths of time. Finally it reached man ; yes, the very 
atoms which thrill and flash in our brains and muscles 






2 MODERN CHEMISTRY 

once formed part of a living plant or animal millions of 
years ago, and will again form part of a living plant or 
animal millions of years hence. In some form or other the 
matter which now forms our bodies will exist long after the 
whole present order of creation has passed away ; indeed, 
it may well yet blow in the winds of worlds as yet unborn, 
and thrill in forms of life not yet evolved. 

This ceaseless round of matter seems to have impressed 
Shakespeare, who has caused Hamlet, not pleasantly, 
to refer to the subject more than once. In Act IV. Scene 3, 
we have the man eating the fish that has fed on a worm, 
which in its turn was sustained upon a dead emperor, and 
are shown " how a king may go a progress through the 
guts of a beggar." In Act V. Scene 1, there is the notable 
speech of Hamlet, when he says, 

" Alexander died, Alexander was 
buried, Alexander returneth into dust : the 
dust is earth. ; of earth we make loam : and 
why of that loam, whereto he was converted, 
might they not stop a beer-barrel ? 
Imperious Caesar, dead and turned to clay, 
Might stop a hole to keep the wind away. 
O, that that earth, which kept the world in awe, 
Should patch a wall to expel the winter's flaw ! " 

! Not only the material forming our bodies, but every piece 
of material around us possesses an antiquity so vast as to 
be almost incredible. What endless convolutions and 
vicissitudes, for example, has a common lump of earth 
passed through before it reached its present form ? It has 
been part of continents which have long since vanished, and 
has borne the tread of races long since extinct. It has been 
on the top of mountains and at the bottom of oceans ; it has 
often formed part of the molten fire underground, and, in 
spite of all this, it still remains, and will remain during 
endless ages yet to come. 

All these wonders arise from the fact, brought to light 
by the patient labours of generations of scientific men, that 
matter is indestructible, that it can be neither generated 
nor destroyed by any means in our power. It may pass 






THE MYSTERY OF MATTER 



into a totally different series of forms, but at the end of a 
whole series of changes the same weight of matter remains 
as was there in the beginning. For example, when a candle 
burns away it disappears, and the matter forming it is 
apparently annihilated ; yet this is not really so, for the 
candle merely burned to invisible gaseous forms of matter, 
which, when collected and weighed, are found to contain 
the same weight of carbon and hydrogen (the kinds of 
matter which make up the 
candle) as was originally 
in the candle itself. This 
latter fact, indeed, can be 
shown easily by means of 
a very simple experiment. 
A candle C is fixed in a 
stoppered bottle A (Fig. i) , 
which is then weighed. 
The candle is now lighted 
by making a platinum wire 
BB, which encircles the 
wick, white hot by means 
of an electric current. The 
candle burns for a short 
time, and then goes out. 
On reweighing the bottle 
when it is cold, no altera- 
tion in weight will be 
found to have occurred, 
although part of the 
candle has burned into 
invisible gas. 

'•" In the light of recent discoveries, however, it may be 
doubted whether matter is absolutely indestructible, but 
there is no doubt that ordinary matter, if decomposable at all, 
decomposes so slowly that a single pound of it will endure 
through millions of millions of centuries, a time longer than 
that required for the whole solar system to evolve.* 
It is indeed hard to conceive that anyone in full possession 
* Sir Oliver Lodge, " Modern Views of Matter " (1903), p. 25. 




Fig. 1. 



4 MODERN CHEMISTRY 

of his senses can look into the heavens on a dark starry 
night and remain unmoved. The fact that he looks into 
a vast void extending upwards for ever and ever, strewn 
with innumerable myriads of suns and world-systems must 
fill even the most brutalised mind with a feeling of awe 
and bewilderment. Yet the interspace between world and 
world is not truly empty in the popular sense for it is fiUed 
with a wonderful medium, termed the ETHER, which fills 
all the depths of space, and bears through it to us, m the 
form of minute ripples or quiverings, the light of the distant 
stars Matter moves through this vast sea of ether appar- 
ently without resistance, much as a sieve moves through 
water or a wind rushes through the trees ; but what 
"matter" is we do not know. AU that we do know 
is that it is totally unlike anything which our crude senses 
conceive it to be, and is probably far more wonderful than 
anything we can even imagine. 

- We know that the solid objects about us are not really 
""solid and impenetrable. They consist of countless millions 

of tiny particles, tiny atoms as chemists call them, m 
uHceasing and swift motion. A single grain of lycopodmm 
powder is made up of over a trillion of such atoms ; earth, 
the paper on which I write, the very air we breathe, consists 
of unimaginable millions of these tiny worlds, rushing and 
revolving as rapidly as rifle buUets. Mendeleef hkens the 
atoms to the heavenly bodies, the stars, sun, planets, satel- 
lites, and comets, and he considers that the building up of 
molecules from atoms, and of substances from molecules, 
resembles the building up of systems, such as the solar 
system, or of twin stars, from these individual bodies. 

— Even these atoms which build up ordinary matter are by 
no means solid masses. Far from it. Each atom is probably 
composed of a few thousands of tiny specks of negatively 
electrified particles, which fly about in astronomical orbits 
inside the atoms (much as a swarm of bees would fly about 
inside the dome of a great cathedral) forming a kind of 
cosmic system under their strong mutual forces, and occu- 
pying the otherwise empty region of space which we call 
the atom. 



THE MYSTERY OF MATTER 5 

The porosity of matter as thus constituted is extreme, 
and this explains why it can move through the ether without 
apparent resistance. Matter hangs in space like a faint 
cloud, and is perhaps a mere misty modification of the 
wonderful space-filling fluid. Indeed, there is reason to 
believe that the one massive constituent of the universe 
is this invisible ether, and that our matter is a mere gauzy 
cob-web, a mist, or a milky-way floating in it. The reason 
why matter appeals to us so strongly and clearly is because 
our bodies are composed of it, and because our sense organs 
have been evolved to respond to its various motions.* 
*■* "Matter," says Francis Galton,f "is a microcosm of 
innumerable and, it may be, immaterial motes, and . . . 
the apparent vacancy of space is a plenum of ether that 
vibrates throughout like a solid." Nor must we forget 
that matter, as we know it, is but a collection of sensations 
generated in our brain by an exciting cause ; the matter 
itself which lies behind and gives rise to these sensations 
remains for ever unknowable, hidden behind the veil of 
changing phenomena. It is none the less real for all that, 
but still the fundamental fact remains that of the outer 
world we know nothing except our sensations. A landscape 
is nothing but a cluster of sensations. So also is a beautiful 
woman, a lovely flower, a child, a book. Between us and 
external reality stands as an impenetrable intermediary, our 
nervous system. When we attempt to understand the 
inmost nature of the outer world we stand before it as 
before utter darkness. Outside of ourselves there exists 
in Nature neither sound nor silence, brightness nor darkness, 
neither colour, odour, space, force, nor anything that we 
know as sensation. The multitudinous sounds of Nature, 
the creaking of carts, the cries of animals, the wail of music, 
the awful roll of thunder, are all produced by the excitement 
of our acoustic nerves, and exist only in our brains. As to 
the excitement itself, there is nothing to indicate that it is 
sonorous. It is in our brain that noise is produced ; outside 

* Sir Oliver Lodge, " The Structure of the Atom," Journal of the 
Society of Chemical Industry (1908), Vol. 27, p. 731. 
f The Times, May 31, 1910. 



I 



6 MODERN CHEMISTRY 

of it reigns eternal silence, or worse, since silence is the 

correlation of noise. Similarly light is produced by the 
excitement of the optic nerve, and shines only in our brains ; 
the ethereal vibrations themselves are not lunnnous. 
Outside us, then, is utter darkness ; the flashing lights and 
colours of the outer world which incessantly assail us the 
sudden glare of lightning, the gleam of gold and scarlet, the 
green of trees and fields, all the visible glories of the outer 
world, exist but in our brain ! The same is true of all our 
other senses, and affects to an unknowable degree our 
conception of matter. We are utterly walled in by our 
nervous system. . , 

^ We will now give a brief account of the views of the fore- 
most modern thinkers upon the constitution of matter. A 
wonderful theory of Professor Osborne Reynolds* assumes 
that the ultimate particles which make up matter are 
nothing but empty cracks flitting to and fro kke silent 
ghosts through the vast stagnant sea of ether. The ether 
is supposed to consist of an arrangement of indefinite 
extent of uniform spherical grains, generally so close that 
the grains cannot change their neighbours, although con- 
tinually in relative motion with each other. The grains 
are extremely minute, the diameters being 5.534x10- 
centimetres (1 inch is 2.5 cms.). The millionth part of an 
inch could contain half a billion such particles packed side 
by side The pressure in the medium is about 10,000 tons 
per square centimetre. In spaces in which there occur a 
smaller number of grains than is necessary to render the 
piling "normal/' such local deficiencies are permanent. 
They can run through the medium without the medium 
moving with them, much as waves pass over water without 
a transfer of matter. They attract each other according 
to the laws of gravitation, and constitute the particles ol 
matter. Hence, in contradistinction to our usual notions, 
matter consists of merely cracks or gaps in space ; it is 
" emptiness," and not " fullness," as one would naturally 
suppose. 

* -The Sub-Mechanics of the Universe," Cambridge University 
Press, 1903- 



THE MYSTERY OF MATTER 7 

This theory gives a complete explanation of gravitation, 
the velocity of light, and numerous other physical phe- 
nomena. 
r* According to another theory, matter is an electrical 
manifestation. It consists in aggregations of electrical 
particles, called by some authors, " electrons," by others, 
" corpuscles." The diameter of these particles has been 
calculated to be only 0.961 x 10- 13 centimetres;* so that 
over 20,000,000 could be packed side by side in the millionth 
of an inch. 

All the different elementary chemical atoms are made up 
of aggregations of many thousands of these minute bodies ; 
these electrons or corpuscles, therefore, correspond to the 
long-sought primary matter or " protyle," out of which 
all the chemical elements are built up. 

According to Larmor, the electrons are nothing but centres 
of strain, probably minute eddies, in the ether. These 
strain centres must not be thought of as parts of the 
medium for ever separated from the rest, for it is the 
strain alone which persists, the part of the ether which is 
affected by it constantly changing as the sub-atom is 
moved. 

In Whetham's words, f " Matter is a persistent strain form 
" flitting through a universal sea of ether, and ether, in its 
" turn, is a close-packed conglomerate of minute grains 
" in continual oscillation. . . . But what of the grains 
" of which the ether is composed ? 

" Are they ' strong in solid singleness ' like the one-time 
" atom of Lucretius ? Or have they parts within which 
" opens a new field of complexity ? Of what substance are 
" they made ? 

" Has a new ether more subtle than the first to be invoked 
" to explain their properties, and a third ether to explain 
" the second ? The mind refuses to rest content at any 
" step of the process. An ultimate explanation of the 
" simplest fact remains, apparently for ever, unattainable." 

* Arrhenius, " Theories of Chemistry " (London), 1907, p. 91. 
f " Recent Advances in Physical Science " (1904), pp. 282-294, 
(Murray). 



8 MODERN CHEMISTRY 

If matter is but a number of minute whirlpools in a 
universal sea of ether, surely by the slow diminution of 
their velocities in the course of ages these whirlpools must 
ultimately die out, again passing into the ether ? The idea 
of the slow passage of matter into ether has been put forward 
by many recent writers, amongst whom may be mentioned 
Le Bon.* According to such a view, the material universe 
must be slowly disappearing. So that even the stately 
world-systems of space are smitten with a process of slow 
decay ; even as the planets circle in silence around their 
central suns, they are rushing into oblivion, and ultimately 
must vanish, like clouds in a summer's sky, leaving 
no wrack behind them to show that they have been and 
gone. We have, however, no experimental proof of this 
view. 

The most fundamental property of matter for dynamical 
science is mass. The mass of a body used to be defined 
as a measure of the quantity of matter it contained. It is 
explained by the electronic theory of matter as an effect of 
electricity in motion. If this is so, it can be shown that 
the mass of a body must increase with its velocity, and, 
indeed, actual experiments by Kaufmann showed that this 
is the case. According to this idea, the mass of a body is 
not invariable, but rapidly increases as its speed approaches 
that of light (3X10- 10 cms. per second, or 186,000 miles 
per second), and were it actually to attain this speed, its 
mass would become infinite. It follows, therefore, that the 
velocity of no material body can exceed that of light. But if 
the velocity is less than the tenth part of this, the difference 
in mass from that at very low velocities is insignificant — 
below one per cent. As a matter of fact (excluding certain 
Cathode and Beta rays), matter is never observed with such 
high velocities. Even when planets crash together in space 
and flash instantly into vast masses of glowing rushing gas 
heated to a temperature almost inconceivable to us, the 
flying masses of ejected matter never attain velocities 
approaching that of light. Thus the eruptions in the new 

* " The Evolution of Matter," by Dr. Gustave Le Bon (London), 
1907. (Kegan Paul, Trench, Triibner & Co.) 



THE MYSTERY OF MATTER 9 

star of Perseus, in 1901, the result of some tremendous 
cosmical collision, did not attain a velocity greater than 
466 miles per second. The greatest observed velocity of the 
huge flames on the sun is 528 miles a second — a velocity 
exceeding that of a rifle bullet nearly a thousand times. 
Tremendous as these velocities seem, they are barely the 
four-hundredth part of the speed of light, so that the 
deviation from the law of constancy of mass must, even 
in these extreme cases, have been insignificant. 
■^ The amount of matter in the universe is so great as to 
defy all comprehension. Our earth alone is a huge globe 
nearly 8,000 miles in diameter, weighing nearly 5.5 times as 
much as an equal bulk of water. The sun exceeds the earth 
nearly 300,000 times as regards mass ; and there exist at 
least 100,000,000 suns visible in a large telescope, some of 
which are larger, some smaller, than our own sun. In 
addition to these visible suns there is, perhaps, an even 
larger number of dark suns, bodies whose existence is only 
revealed to us when they come into collision with other 
bodies and produce the new stars which, from time to time, 
suddenly blaze in the sky. 

" Now, even the smallest grain of dust visible to the eye 
contains nearly a billion atoms of matter. How many atoms 
then, occur in the whole giant bulk of the earth ? How many 
in the whole universe ? If a grain of dust is a wonder heap, 
a structure infinite in its complexity, what shall we say about 
the universe ? 

The whole of this tremendous bulk of matter does not 
consist of the same stuff throughout. Chemists have shown 
that there exist some eighty or ninety distinct kinds of 
matter termed elements. Everything we see about us on 
the earth is built up of atoms of these different elements, 
and the spectroscope tells us that the same 80-90 elements 
also build up the world-systems of space. 

Chemistry is the science which explores this unknown 
world of atoms. In the following chapters will be told the 
wonderful story of how man has succeeded in penetrating 
this universe of the infinitely small, and how he has 
actually determined the size, shape, and structure of particles 



10 



MODERN CHEMISTRY 



so tiny as to be invisible even under the most powerful micro- 
scope ever invented. The chemist of to-day can confidently 
follow the unseen motions of a realm which the scientists of 
a few decades ago had thought for ever unexplorable to the 
intellect of man. 



CHAPTER II 

THE UNDERWORLD OF ATOMS 

ill matter is slowly changing. In the whole of nature there 
is not a single particle in a state of rest. Not a single object 
existing now will exist a few million years hence. Tennyson 
was conscious of these grand cosmic changes that are continu- 
ally altering the surface of the earth when he wrote : — 

" The hills are shadows and they flow 
From form to form and nothing stands ; 
They melt like mist, the solid lands 
Like clouds they shape themselves and go." 

The Greeks were extraordinarily close observers of nature, 
and the eternal changes going on in her did not escape them. 
Thus there sprang up, over 2,300 years ago, a series of great 
thinkers, Leucippus, Democritus, and Epicurus, who 
traced this perpetual change to the motions of the tiny 
atoms of which matter is built. The views of Democritus, 
as elaborated by Epicurus, were centuries later described 
by the Roman, Titus Lucretius Cams (98-54 B.C.), in a poem 
" De Rerum Natura," and surely never before and never 
since has a theory of the universe been set forth in a form so 
resplendent with imagery. In this poem we catch a glimpse 
of that grandeur of the old Greek poetry, which is now for 
the most part lost ; and we realise how boldly and with 
what scientific imagination these old-world thinkers looked 
into Nature's hidden underworld, and, like Tennyson in 
our own time 

" Saw the flaring atom streams 

And torrents of her myriad universe, 

Ruining along the illimitable inane, 

Fly on to crash together, and make 

Another and another frame of thing? 

For ever." 

11 



12 MODERN CHEMISTRY 

According to Lucretius the whole universe consists 
of innumerable multitudes of atoms, extending far 
beyond the limits of our visible world and filling all the 
depths of space. These atoms are not at rest ; far from it ; 
they are falling silently downwards like snowflakes on a 
winter's day, through immeasurable intervals of space and 
time. In one vast moving stream of innumerable myriads 
they come, sweeping out from the heights of unknowable 
immensity above into the infinite depths below ; without 
end or beginning, night and day, year in year out, for all 
time and through all space, this mighty fall continues. 
The atoms, however, do not fall straight down ; for if they 
did " they would all fall down " as Lucretius wrote, " like 
drops of rain through the deep void, and no clashing would 
have been begotten, nor blow produced from the first 
beginnings ; thus nature would never have produced aught." 
Consequently, the atoms as they fall swerve slightly from 
their paths ; they clash together and entangle themselves in 
groups ; then group reacts on group and sets up whirlpools 
of rotating atoms, something after the nature of the astro- 
nomers' nebulae of to-day. 

From such vast whirling eddies of atoms are formed not 
only the solid objects on the earth, but even the earth itself 
and the heavenly bodies. As everywhere throughout all 
space the same conditions are repeated, so must the pheno- 
mena be repeated also. Above us, below us, beside us 
therefore, are worlds without end. Some are great, others 
small ; some are in the process of formation, and others, 
through collision, are being destroyed. Some have many 
moons, others none ; some even are devoid of water. But 
they have all one fate in common, they are all transient. 
These worlds come and go, attracting new atoms out of 
limitless space or dispersing their own particles ; thus 
the universe is in a state of flux in every part. All things 
are fading or growing like clouds in a summer's sky. 

According to Lucretius, the atoms are of different shapes 
and sizes, as well as eternal and indestructible. Though 
ancient systems may be dissolved and new systems evolved 
out of their ruins, the atoms out of which these systems 






THE UNDERWORLD OF ATOMS 13 



are built continue to this day as they were created, unbroken 
and unworn, perfect in number and weight. They are so 
tiny that no mortal eye can ever behold them ; they must be 
so small because, as Lucretius told us : — 

" After the revolution of many years a ring is thinned on the under- 
side by wearing, the dripping from the eaves hollows a stone, the 
bent ploughshare of iron imperceptibly decreases in the fields, and 
we behold the stone-paved streets worn down by the feet of the 
multitude. . . . These things we see are lessened, after they are 
thus worn down ; but what bodies depart at any given time nature 
has jealously shut out the means of seeing. Lastly, the bodies 
which time and nature add things to little by little, constraining them 
to grow in due measure, no exertion of the eyesight can behold ; 
and so too, wherever things grow old by age and decay, and when 
rocks hanging over the sea are eaten away by the fine spray, you 
cannot see what they lose at any given instant. Nature therefore 
works by unseen bodies." 

This smallness of the atoms explains why it is that although 
the atoms which build up a body are in swift motion yet 
the body itself is seen to rest in supreme repose unless it 
exhibits motion as a whole ; 

" For," as Lucretius adds, " the atoms lie far away from our senses, 
beneath their ken ; and therefore since they are themselves beyond 
what you can see, they must withdraw from sight their motions also ; 
and the more so since the things which we can see, do often conceal 
their motions when a great distance off. For often the woolly flocks 
as they crop the glad pastures on a hill, creep on whither the grass 
jewelled with fresh dew summons and invites each, and the lambs 
fed to the full gambol and playfully butt ; all which objects appear 
to us from a distance to be blended together and to rest like a white 
spot on a green hill. Again when mighty legions fill with their 
movements all parts of the plains, waging the mimicry of war, the 
glitter then lifts itself up to the sky and the whole earth round 
gleams with brass and beneath a noise is raised by the mighty tramp- 
ling of men, and the mountain side stricken by the shouting re-echoes 
the voices to the stars of heaven, and horsemen fly about and 
suddenly wheeling scour across the middle of the plains, shaking 
them with the vehemence of their charge. And yet there is some spot 
on the high hills, seen from which they seem to stand still and rest 
on the plains as a bright spot." 

Modern science now tells us that this reasoning is correct, 
the motion of molecules in the case of solid bodies being 
confined within so narrow a range that even with our best 



14 MODERN CHEMISTRY 

microscopes we cannot detect that they alter their places 
at all. Lucretius illustrated the ceaseless whirl and the 
eternal clash of the atoms which make up all bodies about 
us by the familiar spectacle of motes dancing in a sunbeam ; 
he wrote : — 

" Of this truth . . . we have a representation and picture always 
going on before our eyes and present to us ; observe whenever rays 
are let in and pour the sunlight through the dark chambers of houses : 
you will see many minute bodies in many ways through the apparent 
void mingle in the midst of the light of the rays, and as in never ending 
conflict skirmish and give battle, combating in troops and never 
halting, driven about in frequent meetings and partings."* 

But here we must stop ; for enough has been said to show 
the reader that Democritus was the greatest of the ancient 
thinkers, whose views, obscurely expressed by partisan 
philosophers, more closely approximate in their grandeur 
and loftiness to modern theories than those of any of his 
successors for the space of nearly two thousand years after 
his death. Not only did he clearly set forth the atomic 
theory now universally acknowledged, but he, as we have 
just seen, believed the sun to be of enormous size, that the 
Milky Way consisted of suns, and that the number of worlds 
was infinite — ideas finally arrived at only within the last 
couple of centuries by European scientists ! 

For two thousand years these speculations of the Greeks 
remained buried and almost forgotten. Newton was 
acquainted with them and appeared to have accepted the 
idea that all bodies are made up of hard indestructible par- 
ticles. " It seems," says Newton, " probable to me that 
God in the beginning formed matter in solid, hard, impene- 
trable, movable particles, of such sizes and figures, and with 
such other properties, and in such proportion, as most con- 
duced to the end for which he formed them ; and that these 
solid particles, being solids, are incomparably harder than 
any porous bodies compounded of them ; even so very hard 
as never to wear or break in pieces, no ordinary power being 

* The reader will find an interesting account'of the earlier chemical 
theories in Ida Freund's " The Study of Chemical Composition/' 
and in Muir's " History of Chemical Laws and Theories." 



THE UNDERWORLD OF ATOMS 15 

able to divide what God himself made one in the first crea- 
tion/'* 

It is, however, to Dalton and to him alone that the honour 
of founding a CHEMICAL atomic theory is to be ascribed. 
It had long been known that, just as men and women are 
attracted to each other and unite as husband and wife, so 
also in the atomic world the atoms combine to form little 
groups called " molecules." The molecules are, so to speak, 
the planetary systems which build up all the objects around 
us. Now it was Dalton who discovered in 1803 that there 
was as little chance or haphazard in the concourse of the 
atoms as in the motions of the planets. Before his time it 
had been well known that chemical compounds, that is 
substances resulting from the union of the atoms of two or 
more elements, have a fixed composition. In other words 
a chemical compound is not a product like a plum pudding, 
in which the proportion of the ingredients which make it 
up can be varied considerably without much affecting its pro- 
perties. Quite otherwise. We cannot vary even in the 
slightest degree the ratio in which the elements are combined 
in a true compound. This fact is known in chemistry as the 
Law of Constant Proportions. Dalton's great discovery was 
the Law of Multiple Proportions. This is best explained by 
means of an example. Iron can combine with sulphur in 
two proportions to form two different compounds, one a 
black body called ferrous sulphide, the other a brass-like 
substance called iron pyrites. When these bodies are ana- 
lysed a very remarkable fact comes to light. The first body 
consists of ONE part of sulphur combined with 1.74 parts of 
iron. The second body consists of TWO parts of sulphur 
combined with 1.74 parts of iron. So that the amount of 
sulphur combined with the same weight of iron in the two 
compounds is EXACTLY in the ratio 1 : 2, i.e. in the ratio 
of simple whole numbers. Again, nitrogen combines with 
oxygen to form several different bodies, and the weights of 
oxygen which are united with 1.75 parts of nitrogen are, 
1, 2, 3, 4, 5, respectively, in the successive compounds. Here 
again the ratio of the weights of oxygen which are combined 
* Horsley's "Newton," Vol. 4, p. 260. 



i6 



MODERN CHEMISTRY 



with a fixed weight of nitrogen, are simple whole numbers. 
Now Dalton showed that this was a general law, which may be 
stated thus : Whenever two elements unite to form several 
different compounds, the ratios of the different weights of the 
first element which unites with a fixed weight of the second 
are always simple WHOLE numbers. 

Why the ratios should be exactly whole numbers and not 
fractional, seemed an inexplicable mystera until Dalton 
showed that it was a necessary consequence of the atomic 
theory. In the case of iron, for example, we have the 
following two compounds produced by the union of atoms 
of iron and sulphur. 




□ 









- • 


1 


v!v 




v 






> 









Iron. Sulphur. 



Iron. Sulphur, 



Since two atoms of sulphur weigh exactly twice as much 
as one, it is obvious now that the ratio of sulphur combined 
with the same weight (for example, one atom) of iron must 
be in the ratio i : 2, i.e. exactly whole numbers. 

Dalton's great feat was the application of the atomic theory 
to chemistry. Although the ancient theory of the structure 
of material things had predicated differences in the sizes and 
weights of the different kinds of atoms, yet Dalton was 
the first who demonstrated that it is actually possible to 
determine the relative weights of the atoms of elements, and 
the number of atoms which constitute the ultimate particles 
of compounds. The theory, however, was not launched 
perfect into the world ; it still contained many grave errors 
and uncertainties. Dalton, for example, had imagined 
that the elementary gases like oxygen or nitrogen consisted 
of single atoms moving about rapidly ; but in 1811 Avo- 
gadro, an Italian physicist, showed that what Dalton had 
called an " atom " usually consisted of two separate atoms 
united together and accompanying each other on their 
journev through space, like man and wife or earth and moon. 



THE UNDERWORLD OF ATOMS 17 

Again, it had been known for some time that water consists 
of 8 parts of oxygen united with 1 part of hydrogen. Dalton 
asserted that water consisted of one atom of oxygen united 
with one atom of hydrogen, and that therefore the atom of 
oxygen weighed 8 times as much as the atom of hydrogen. 
Avogadro, however, showed that water, in reality, consists 
of two atoms of hydrogen united with one atom of oxygen, 
and that therefore an atom of oxygen weighs 16 times as 
much as an atom of hydrogen. The Italian was thus the 
first to point out the modern distinction between " atom " 
and " molecule " ; it was he who showed clearly how the 
relative weight of the different kinds of atoms and mole- 
cules may be determined with certainty and without 
ambiguity. " An atom/' says Maxwell,* " is a body which 
cannot be cut in two. A molecule is the smallest possible 
portion of a particular substance. No one has ever seen or 
handled a single molecule. Molecular science, therefore, 
is one of those branches of study which deals with things 
invisible and imperceptible by our senses, and which cannot 
be subjected to direct experiment. . . . Molecule is a modern 
word. It does not occur in Johnson's Dictionary. The 
ideas it embodies are those belonging to modern chemistry. 
A drop of water . . . may be divided into a certain number, 
and no more, of portions similar to each other. Each of 
these the modern chemist calls a molecule of water. But it 
is by no means an atom, for it contains two different sub- 
stances, oxygen and hydrogen, and by a certain process the 
molecule may actually be divided into two parts, one con- 
sisting of oxygen and the other of hydrogen. According 
to the received doctrine, in each molecule of water there are 
two atoms f of hydrogen and one of oxygen. . . . We now 
see what a molecule is as distinguished from an atom. A 
molecule of a substance is such a small body that if, on the 
one hand, a number of similar molecules are assembled to- 
gether they would form a mass of that substance, while on 
the other hand, if any portion of this molecule were removed 

* " Scientific Papers," Vol. 2, p. 361. 

f Maxwell here says " molecules." I have ventured to alter the 
word to " atom " in conformity to modern usage, 

B* 



18 MODERN CHEMISTRY 

it would no longer be able, along with an assemblance of 
other molecules similarly treated, to make up a mass of 
the original substance. Every substance, simple or com- 
pound, has its own molecule. If this molecule be divided, its 
parts are molecules of a different substance or substances 
from that of which the whole is a molecule. An atom, if 
there is such a thing, must be a molecule of an elementary 
substance." 

Avogadro's ideas were not accepted until nearly half a 
century after his death. 

For many years after Dalton's time the atomic theory 
was still in a very imperfect condition. Such incredible 
qualities, as infinite smallness, absolute hardness, and 
indivisibility, were attributed to the atoms that many 
reasonable naturalists were inclined to doubt whether they 
were real entities at all. Even in the early days of the 
theory, however, many first-class intellects were pondering 
over these problems. If atoms are infinitely small, why 
are not all chemical reactions infinitely swift ? asked Sir 
William Thomson ; and he suggested that atoms are real 
portions of matter occupying a finite space and forming a 
not immeasurably small constituent of any palpable matter. 
Proof after proof of the fundamental correctness of this 
view gradually collected. First of all Loschmidt in 1865 
showed how it followed from the kinetic theory of gases that 
molecules have a sensible diameter, and he actually deduced 
a numerical value for it. Then Johnstone Stoney in 1868, 
and later, Sir William Thomson in 1870, published results 
of a similar kind, — those of Thomson being deduced not 
only in this way, but from considerations derived from 
the thickness of soap bubbles, and from the electric action 
between zinc and copper. 

The diameter and mass of a molecule, as estimated by 
these methods, are very small, but by no means infinitely 
so. About two millions of hydrogen molecules in a row would 
occupy a millimetre (25.4 millimetres going to an inch), 
and two hundred million million million of them would 
weigh a milligramme. " To form some conception," says 
Thomson," of the degree of coarse-grainedness indicated 



THE UNDERWORLD OF ATOMS 19 

by this conclusion, imagine a rain drop, or a globe of glass 
as large as a pea, to be magnified up to the size of the earth, 
each constituent molecule being magnified in the same 
proportion. The magnified structure would be more coarse- 
grained than a heap of small shot, but probably less coarse 
grained than a heap of cricket-balls."* 

Dr. Johnstone Stoney (Phil. Mag., 1868, Vol. XL., p. 382) 
employs the following remarkable illustration of the size 
of the molecules : — 

" A cubic millimetre, the volume of a small pin's head, if each of 
its edges were magnified io 10 times (i.e. 1 followed by 10 noughts), 
would become almost as huge as the earth. Under the same circum- 
stances molecules of air would be spaced at intervals averaging 10 
metres (nearly 11 yards). And 700 metres would have to become 
the mean distance to which they would have to travel between 
their encounters. On this great scale it would not be inappropriate 
to use men or other animals to represent the individual molecules — 
their hearts beating, their chests heaving, their limbs in vigorous 
motion, to represent their internal events (motions). And as to the 
motions with which the molecules of a gas dart about among one 
another, these as they exist in common air would have become 
journeys as long and of as various lengths as the streets of a great 
city, while the widths of the streets may stand for the intervals at 
which the representatives of the molecules are to be spaced asunder 
at starting. In this model we have applied so much more magnifi- 
cation to time than to space that all the velocities come out 6oj<ooo 
times slower than in nature. Accordingly our animated molecules 
may be conceived as quietly gliding along the journeys they have 
to make between their encounters ; for the mean duration of a 
journey is to be a day and the average speed must accordingly be only 
half a metre a minute — on the supposition that our model is to repre- 
sent what occurs in a gas as dense as air and at its temperature and 
pressure. It thus appears that we must conceive them as requiring 
on the average about a quarter of an hour to get past each house in 
the streets along which they have so slowly to make their way. A 
model of this kind is not without its use, if only as a means by which 
we can gain a lively perception of how considerable the events going 
on within the molecules may be when compared with the motion oi 
translation of the molecules." 

Molecular science thus brings us face to face with the 
mystery of living matter ; it forbids the physiologist from 
imagining that structural details of molecular dimensions 
* Nature (1870). 



20 MODERN CHEMISTRY 

can furnish an explanation of the infinite variety which exists 
in the properties and functions of the most minute organisms. 
For, according to Clerk Maxwell,* the smallest living 
germ visible under the microscope contains barely a million 
organic molecules, — a number far too small to form a being 
furnished with a whole system of specialised organs. Yet 
from this germ will develop a highly organised animal 
and from another germ, equally microscopic, will develop 
another animal of a totally different kind — an idea well 
expressed by Sir Lewis Morris in the words : — 

" Within the germ the molecules fare free, 
Holding the potency of what shall be ; 
Within the little germ lurks the heaven-reaching tree." 

We may therefore well ask, Can all the differences, infinite 
in number, which distinguish the one animal from the other, 
arise each from some difference in the molecular constitution 
of the respective germs, structures containing barely a 
million molecules ? This seems scarcely possible. It 
appears, therefore, that life must take its rise in a world 
beneath the atom, a world composed of particles as small 
in relation to the atoms as the atoms are small in relation 
to ordinary matter particles, f 

Science has done more than measure the mass and size 
of particles so small as to be absolutely invisible under the 
best microscope. She has also measured the velocity with 
which these particles move. According to the molecular 
theory all gases consist of molecules flying about in all 
directions with great speeds. At each instant an incredibly 
vast number crash up against the walls of the vessel con- 
taining the gas, and thus communicate to them a series of 
impulses which follow each other in such rapid succession 
that they produce an effect which cannot be distinguished 
from that of a continuous pressure. This is the reason 
why air or other gas placed in a vessel presses against 
the sides of the vessel ; and from a knowledge of the 

* " Scientific Papers," Vol. 2, p. 461. 

f See an interesting correspondence in The Times, May 30 to June, 
1910, between Francis Galton, Lancester, Pearson, and others. 






THE UNDERWORLD OF ATOMS 21 

pressure and the mass of gas producing it, we can calculate 
the velocity of the gaseous molecule. Let us take the best 
ascertained case, — that of hydrogen gas. A cubic centi- 
metre of hydrogen gas, at the temperature of melting ice 
and at a pressure of one atmosphere, weighs 0.000,089,54 
grams. We have to find out how fast this small mass must 
move (whether together or in separate molecules makes no 
difference) so as to produce the observed pressure on the 
sides of a cubic centimetre. (The result is 1,859 metres a 
second — over a mile a second. This is a very great velocity. 
Even the swiftest rifle bullet does not fly at this rate. 

In other gases the velocity is less. In the case of air it is 
something like 17 miles a minute. 

^Consider for an instant what this means. If all the 
molecules in the air we breathe were flying in the 
same direction they would constitute a wind blowing at 
the rate of seventeen miles a minute. Such a wind has the 
force of a gunpowder explosion. If it struck us it would 
instantly tear us limb from limb and pulverise our bodies. 
Only the fiery blast from a cannon's mouth rushes forth 
with such a velocity. How then are we able to exist in the 
midst of this storm of crashing molecules ? Only because 
they happen to be flying in different directions, so that 
those which are beating against our backs enable us to sup- 
port those which are flashing against our breasts. Indeed 
if the molecules were suddenly to cease their terrific bombard- 
ment, our veins would swell out and burst, the breath 
would rush from our bodies, and we should instantly expire.* 
-^ Tremendous as the velocities reigning in the molecular 
world may seem to us at first sight, yet they are quite insig- 
nificant when compared to the swiftness of the whirling 
motions going on within the atoms themselves ; the particles 
building up the atoms flash through over a HUNDRED 
THOUSAND MILES A SECOND ! Incredible ! you will 
say ; nevertheless it is a sober fact of science. In every 
stone and in every stick about us, ceaselessly, second by 
second, day by day, century by century, age by age, these 

* Clerk Maxwell, " Scientific Papers," Vol. II., p. 366. 



22 MODERN CHEMISTRY 

terrific motions are going on. In the tiniest grain of dust 
in the millionth part of a second the rush of atomic events is 
so incredibly swift as to defy all conception and calculation. 
We have seen above that the apparent repose of the objects 
about us is a false impression, arising from the inability of 
our unaided senses to perceive atomic motion. We know, 
for example, that a regular volcanic action must be going 
on all over the surface of an apparently smooth sheet of 
water. Billions of atoms must be rushing upwards each 
second from each part of the surface, churning it up into a 
million jetting fountains ; and billions of molecules must be 
simultaneously showering downwards, setting up in it 
violent wave motions and eddies. 

The smoothest water surface therefore must, if magnified 
sufficiently, look like a sea torn up and shattered by a 
tornado. 

J^ Dr. Brown, nearly a century ago, was the first who experi- 
mentally demonstrated the existence of this molecular 
motion in water. He suspended very tiny drops of oil in 
water and then examined the mixture through a very 
powerful microscope. The individual drops, instead of 
remaining quietly at rest, were seen to be continually agi- 
tated with small but rapid oscillatory motions. Since the 
smallest drop of oil visible under the microscope must have 
contained something like 50,000,000 molecules, we can form 
some idea of the violent movement which must be going on 
among the neighbouring water molecules in order to set 
into motion such, relatively speaking, bulky masses. 

-^- Recently a method has been discovered which allows us 
to observe the motion of particles far smaller than these 
tiny oil-drops, particles whose magnitudes actually approach 
those of the larger known molecules. Indeed, it is claimed 
that the large molecules of albumen and certain fluorescent 
substances have actually been seen. 

' The principle of this new and beautiful instrument, called 
the ultra-microscope, is as follows : — Before we can see an 
object it must reflect to us the light by which we see it. 
Objects which reflect no light are invisible. Now a grain of 
sard will not reflect an ocean wave because it is too small 



THE UNDERWORLD OF ATOMS 



23 



in respect to it. The wave simply embraces the sand and 
passes on. In the same way particles much smaller than 
waves of light will not reflect them at all and so cannot be 
seen in the strongest microsope. In fact it has been proved 
that the smallest particles which can be seen in the best 
modern microscopes are about Wroth of a millimetre in 
diameter, just about half the length of a wave of visible 
light. We can never hope, therefore, to see directly a par- 
ticle as small as a molecule, since these are many thousands 




Fig. 2. — Use of the Ultra Microscope, 



of times smaller in diameter than the length of a wave of 

light. 

s* The case is otherwise, however, if we make these particles 

emit a light of their own. Then we may get from them the 

light necessary to see them. 

^ In order to do this a beam of sunlight is brought to a focus 

in the liquid containing the particles. The apex of this 

cone of light is observed by a special microscope ; the intense 

beam of light falling on the particles sets them into a vibra- 



24 MODERN CHEMISTRY 

tion so intense that they emit a light of their own by which 
they may be seen. 

Zsigmondy* obtained suspended in water gold dust so 
fine that many particles could not have contained more 
than a few dozen molecules. On looking at these tiny 
particles through the ultra-microscope, he saw them in swift 
motion. 

" The tiny gold particles did not swing stationary in the water, they 
moved with astonishing rapidity. He who has seen a swarm of flies 
dancing in the sunlight can obtain a notion of the motions of these 
tiny gold particles ; they hop, dance, spring, crash together and fly 
apart so rapidly that the eye can hardly make out their movements. 
. . . These motions show that there is a continual mixing together of 
the interior parts of every liquid, g&ing on unceasingly, year in, year 
out. . . . The smallest observable gold particles show a double 
motion ; firstly they possess a motion of translation so rapid that 
the particles travel ioo to iooo times their own diameter in ^ to ^ 
of a second ; secondly, they possess a swinging or oscillatory motion 
of much shorter period; indeed it is probable that they possess 
oscillatory motions of higher order and smaller amplitude, too small 
and too rapid for airect observation." 

The appearance of a similar silver dust in water is described 
as follows :— 

** " One would never guess what a wonderfully beautiful play of 
colours is given out by this ordinary looking liquid when viewed 
through the ultra-microscope. Blue, violet, green, and red particles, 
in different shades and with a rare brilliancy of colour, are seen in 
ceaseless movement. One particle approaches the other, circles 
round it in a rapid zig-zag movement, and then flies off again. Some- 
times several particles group together and dance like flies in the 
sunshine, especially when for a fraction of a second one particle 
comes near another." 

s Zsigmondy thus describes the effect of adding a little 
sodium nitrate to a clear gold solution so as to make the 
particles of gold coagulate : — 

" Suddenly there appeared yellow balls of mist, in a state of wave 
mo! ion. The mist condenses further. One sees the tiny individual 
particles in a state of lively Brownian movement. The particles rush 

* Zsigmondy, " Kolloidie und Ultramicroskopie " (1905). z.f. 
Eloktrochemie viii. 684-87 (1902). z.f. Physik. Ch. lvi. 65-82 (1906). 
An American translation of these researches has recently appeared. 



THE UNDERWORLD OF ATOMS 25 

together and revolve round their common centre of gravity. . . if 
the saltpetre solution be allowed to flow into the gold solution under 
the microscope, such rapid and violent whirlpool motions are set 
up that the eye is unable to follow the process of coagulation." 

The motions thus revealed in Zsigmondy and Siedentopf 's 
researches must be regarded as the beginnings of the finer 
and swifter molecular motion going on in all bodies about us. 
The molecules themselves must, at ordinary temperatures, 
move so rapidly (some hundreds of yards a second) that it 
would be impossible to follow them with the eye, even if 
we had the means of visualising their motion. By intense 
cooling, however, it might be possible to slow down their 
motion and thus render them accessible to human observa- 
nt ion. 

~~^ In science nothing is impossible. The nineteenth century 
witnessed the performance of what philosophers had long 
considered utterly impossible, namely, the chemical analysis 
of the sun and stars, bodies millions of miles distant. Will 
not the twentieth century witness a similar triumph, that 
is, the revelation to the eye of the swift-moving atomic 
universe by which we are surrounded ? 
--^We now propose to give the reader a glimpse of a wonderful 
realm of science, a realm which one would have thought must 
for ever have remained unexplored by the intellect of man. 
No one in his wildest dreams would ever have conceived that 
chemists could determine the actual shape of particles so 
small that the largest probably possesses a diameter far less 
than the g sooSoooa part of an inch (io -8 cm.), particles far 
smaller than the very light waves by which we see, so small 
that we can never hope to catch a glimpse of them in the very 
best modern microscopes. And yet this has been achieved, 
and is, perhaps, one of the most wonderful feats of the nine- 
teenth century. Like all great discoveries, however, the prin- 
ciples upon which it rests are simple in the extreme, as we 
will immediately show. 

\Each atom attracts to itself one or more little electric 
moons or satellites, which form the centres to which other 
atoms are attached when the atom enters into chemical 
combination. Now these tiny electrified particles mutually 



26 



MODERN CHEMISTRY 



repel each other, and they consequently take up places on 
the surface of the atom equidistant from each other, and so 
give the atom a definite shape. We will take the case of 
the best studied atom — that of the element carbon. This 
atom is tetravalent ; in other words it can combine simul- 
taneously with four atoms like those of hydrogen or chlorine. 
Consequently it possesses four of these electrified particles — 
electrons we will call them henceforth — attached to it, which 

by their mutual re- 
pulsions assume the 
positions shown in 
Fig. 3 ; that is to 
say, they occupy the 
corners of a tetrahe- 
don, as the figure 
marked out by the 
dotted line is called. 
These electric 
charges, by their at- 
traction, cause other 
atoms to cling to 
them ; and in this 
sense the carbon atom 
maybe said to possess 
a definite shape — 
that of a tetrahedon. 
It must be remem- 
bered, however, that 
it is not the shape 
of the carbon atom, 
but rather the distribution of its electric charges that 
we are, in reality, investigating. Nor must it be supposed 
that these electrons are motionless. Quite the contrary. 
We know that they are whirling with enormous speeds 
— almost with the velocity of light itself — round little 
orbits about fixed points on the carbon atom. In fact 
the tiny atoms are alive with motion and undoubtedly 
possess very complex structures. This conclusion is sup- 
ported by the extremely complex nature of the light they give 




Fig. 3. — Shape of the Carbon Atom according 
to the Modern Electron Theory. Four 
electrons, 1, 2, 3, 4, mutually repel each 
other into the corners of a tetrahedron, the 
centre of which is occupied by the carbon 
atom. 



THE UNDERWORLD OF ATOMS 



27 



out — as will be shown later. This is the view now adopted 
by the majority of chemists. 

However, some of the great organic chemists — Wislicenus, 
for example — have thought that the actual shape of a 
carbon atom is that of a tetrahedron, being composed of 
great multitudes of tiny particles of matter clustered together 
in that form. We have drawn the carbon atom after the 
ideas of Wislicenus (Fig. 

The reader, how- 
ever, should not 
go away with the 
idea that the shape 
of the carbon 
atom is necessarily 
the same at 
all temperatures 
and pressures and 
under all conceiv- 
able conditions. 
Professor J. J. 
Thomson (Phil. 
Mag. 1904, Vol. 7, 
p. 265) has shown 
that if a system 
containing four 
electrons at the 
corners of a tetrahedron be caused to rotate very rapidly, 
they would pass to the corners of a square, thus — 

O O 



mm 



Fig. 4. — Shape of the Carbon Atom according 
to Wislicenus. He supposed that the carbon 
atom was built up in the form of a tetrahe- 
dron, as shown, by the aggregation of a large 
number of small particles. 



o 



o 



On the motion gradually slowing down, this position 
would become unstable, and the particles would suddenly 
revert to their original positions at the corner of a tetrahedon. 

When an element changes its valency, or power of combina- 
tion, it also must necessarily change its shape. No doubt 
very high temperatures, perhaps even immense pressures, 



28 



MODERN CHEMISTRY 



alter tfie properties of the elements entirely. When we 
send a beam of plane polarised light (that is, one in which 
the ether particles all oscillate in one plane) through certain 
substances we often find that the vast whirling motions going 
on within the molecules of the substance caused the beam 
to issue with its plane of polarisation rotated through an 
angle. Suppose now we take a substance whose molecules 
consist of a central atom of carbon, to which are attached 

four different 
atoms or atomic 
groups, which we 
will call R l9 R„ 
R 3 , R 4 , thus:— 



\ 






> 



^2 



R, 



B 



< 



M 



R, 



Fig. 5. R / 

Crystals which when Crystals which when 4 
dissolved in water dissolved in water 

turn the plane of turn the plane of Then we find 

polarisation to the polarisation to the ^ ^^ always 

there exist two j 
sorts of molecules, chemically alike, but which differ in the 
following respects : — 

The first sort, when dissolved in wau rotate the plane 
of polarisation from left to right ; whereas the second sort 
rotate it from right to left — in the opposite direction, and 
to the same extent as well. 

Moreover it sometimes happens that the two substances 
differ from each other in the same way that the right hand 
differs from the left. Fig. 5 shows the crystals of one of 
these substances, known as potassium tartrate. One is 
the mirror image of the other. From this Pasteur, who 
discovered the fact, drew the inference that the difference 
between the two varieties must be due to the different 
arrangement in space of the atoms in the molecules of the 
two crystals. But it was Le Bel and van't Hoff who directly 
connected this fact with the shape of the carbon atom. 
Thus in Fig. 6 ; if we suppose each of the atoms to be 






THE UNDERWORLD OF ATOMS 



29 



arranged round the carbon atom as in (1) ; then in (2) the 
atoms would be arranged round in a directly opposite way, 
so that (1) is a mirror image of (2). This is, probably, the 
explanation of this remarkable effect. But the reader must 
also remember that the exact nature of the cause which 
determines that the light should be rotated from its original 
plane of polarisation is hardly known at all. There must be 
a vast atomic whirl going on in the first case from left to 
right, and in the second from right to left. The medium is, 
as it were, twisted in opposite directions in the two cases. 

Nor is the element carbon alone in this respect. The 
classical researches of Kipping, Pope, and their pupils have 
shown that . . . the atoms 
of such bodies as silicon, tin, 
julphur, and nitrogen all ex- 
hibit " optical activity," as 
the phenomenon is called, 
and so possess a definite 
shape. 

Of course, before optical 
activity can be exhibited, the 
various atoms must be at- 
tached stably to the central 
atom, so that they cannot 
move over its surface and interchange places. In many 
cases where the atoms are light, they move so freely over the 
surface of the central atom and so easily interchange their 
relative positions that optical activity under such circum- 
stances is quite impossible, or if attained, rapidly and 
spontaneously disappears. 

There exist many other cases where the ordinary plane 
formulae are unable to explain the properties of certain com- 
pounds. Their peculiar behaviour, both as regards their 
chemical and physical properties, can only be understood 
on the assumption that they arise out of the different 
positions in space of the atoms in their molecules. Out of 
these facts has grown the fascinating science of " Stereo- 
Chemistry/' but it is far too large a subject to be further 
iealt with here. 




3 B 



Fig. 6. 




30 MODERN CHEMISTRY 

I hope my reader now realises what a wonderful structure 
a tiny molecule must possess. Within this tiny scrap of 
matter lies hidden a whole universe in a ceaseless and terrific 
movement. In Professor Shenstone's words. " The atoms 
move within the molecules, perhaps like the members of 
the heavenly systems — or as suggested years ago by the late 
Professor Williamson, they may even move from molecule 
to molecule in an unending course of migrations ! If so 
. . . stereo-chemical formulae will have to be replaced, 
sooner or later, by living pictures, for which models may 
perhaps be found in the constellations which glorify the 
heavens."* 

* (Shenstone, " The New Chemistry and Physics," p. 286). 
Published by Smith, Elder & Co., London. 



CHAPTER III 

DISTRIBUTION AND EVOLUTION OF THE ELEMENTS 

The search for that which remains unchanged beneath the 
ceaseless flow of chemical change is as old as human thought 
itself, and deeply troubled 

" The hoary thinkers of the Past 
Whose dim vast thoughts, to too great stature grown 
Flashed round as fitful lightning flashes round 
The black vault of the unknown."* 

After many thousands of years of experiment and specu 
lation, it has come to be recognised within the last two 01 
three hundred years that all the changing forms of mattei 
about us are composed of changeless kinds of matter called 
" Elements." A chemical element may be defined as a 
substance which, though it may pass through many trans- 
formations, is always recoverable undiminished in quantity 
from any chemical combination into which it may enter, 
and is not by any known means resolvable into two or more 
kinds of matter. Gold, for example, is regarded as an element 
because from it nothing can be extracted that is not gold ; 
in other words it is homogeneous, and consists in its most 
minute parts of one kind of substance. f Water, and iron 
rust, however, are compounds, because in proportion as 
they are destroyed by suitable means, two kinds of new 
matter make their appearance, and the united weights of 
the products of decomposition are equal to the weight of the 
r compound " body from which they are produced. 

The materials from which this grey old world of ours and 
its inhabitants are built up may be resolved into some eighty 

* Sir Lewis Morris, " The Wanderer." (Published by Kegan Paul* 
Trench & Co.) 

f To what extent this definition of an element must be modified 
owing to the discovery that certain elements like radium are decom- 
posing slowly will be seen later. 

3i 



32 



MODERN CHEMISTRY 



odd elements, a list of which, together with their symbols 
and atomic weights, is here appended. 





LIST OF 


ELEMENTS 








With their 


Symbols 


and Atomic 


Weights. 








o = 16. 






= 16 


Aluminium 


.. Al 


27.1 


Molybdenum . . Mo 


96.0 


Antimony- 


.. Sb 


120.2 


Neodymium . . Nd 


144-3 


Argon 


.. A 


39-9 


Neon 


.. Ne 


20 


Arsenic 


.. As 


75-o 


Nickel 


.. Ni 


58.68 


Barium 


.. Ba 


137-37 


Nitrogen . 


.. N 


14.01 


Bismuth . . 


.. Bi 


208.0 


Osmium . 


.. Os 


190.9 


Boron 


.. B 


ii-o 


Oxygen 


.. O 


16.00 


Bromine . . 


.. Br 


79.92 


Palladium 


... Pd 


106.7 


Cadmium 


.. Cd 


112.40 


Phosphorus . . P 


310 


Caesium ... 


.. Cs 


132.81 


Platinum . 


.. Pt 


195.0 


Calcium . . 


.. Ca 


40.09 


Potassium 


.. K 


39.10 


Carbon 


.. C 


12.00 


Praseodymium . . Pr 


140.6 


Cerium 


.. Ce 


140.25 


Radium . 


.. Ra 


226.4 


Chlorine . . 


.. CI 


35-46 


Rhodium . 


.,. Rh 


102.9 


Chromium 


.. Cr 


52.1 


Rubidium 


.. Rb 


8545 


Cobalt 


.. Co 


58.97 


Ruthenium 


.. Ru 


101.7 


Columbium 


.. Cb 


93-5 


Samarium 


.. Sa 


150.4 


Copper 


.. Cu 


63-57 


Scandium . 


.. Sc 


44.1 


Dysprosium 


..Dy 


162.5 


Selenium . 


.. Se 


79.2 


Erbium . . 


.. Er 


167.4 


Silicon 


.. Si 


28.14 


Europium 


.. Eu 


152.0 


Silver 


..Ag 


107.88 


Fluorine . . 


.. F 


19.0 


Sodium 


.. Na 


23.00 


Gadolinium 


.. Gd 


157-3 


Strontium 


.. Sr 


87.62 


Gallium . . 


. . Ga 


69.9 


Sulphur . 


.. S 


32.07 


Germanium 


.. Ge 


72.5 


Tantalum . 


.. Ta 


181.0 


Glucinum 


.. Gl 


9.1 


Tellurium 


.. Te 


127.5 


Gold 


.. Au 


197.2 


Terbium „. . . Tb 


159-2 


Helium 


.. He 


4.0 


Thallium . 


.. Tl 


204.0 


Hydrogen 


.. H 


1.008 


Thorium . 


.. Th 


232.42 


Indium 


.. In 


114.8 


Thulium . 


. . Tir. 


168.5 


Iodine 


.. I 


126.92 


Tin 


.. Sn 


119. 


Iridium . . 


.. Ir 


193- 1 


Titanium . 


.. Ti 


48.1 


Iron 


.. Fe 


55-85 


Tungsten . 


.. W 


184.0 


Krypton . . 


.. Kr 


81.8 


Uranium . 


.. U 


238.5 


Lanthanum 


.. La 


139.0 


Vanadium 


.. V 


51-2 


Lead 


. . Pb 


207.10 


Xenon 


.. Xe 


128 


Lithium . . 


.. Li 


7.00 


Ytterbium 






Lutecium 


.. Lu 


174 


(Neoyt 


terbium) Yb 


172 


Magnesium 


••Mg 


24.32 


Yttrium . 


.. Y 


89.0 


Manganese 


.. Mn 


54-93 


Zinc 


» . Zn 


65-37 


Mercury . . 


.. Hg 


200.0 


Zirconium 


.. Zr 


90.6 



ELEMENTS— DISTRIBUTION AND EVOLUTION 33 

These elements occur in very unequal proportions. Some 
are so rare and costly that no man has ever gathered more 
than a trace of them ; others are so plentiful that they 
surround us on all sides on land, sea, and sky in innumerable 
millions of tons, and awaken our astonishment by their 
very abundance. The solid crust of the earth is composed 
of eight principal elements, namely, oxygen (47%), silicon 
(28%), aluminium (8%), iron (5%), calcium (3i%) mag- 
nesium (3 %), potassium (2.3 %) and sodium (2.6 %). Besides 
these there occur traces of all the others mentioned in our 
list. This distribution of elements holds only for the outer 
crust of the earth. When we go deep down into its interior 
the distribution alters entirely. The subject has been 
discussed recently by the Swedish chemist Arrhenius* who 
shows that we have good reason to believe that the earth is 
a huge metallic ball, white hot, even gaseous, in the inside. 
In its deepest depths have gravitated together the heaviest 
metals like gold and silver. It will probably excite the 
cupidity of the purse-proud to know that the centre of the 
earth may well be one stupendous gold nugget, or may 
consist of millions upon millions of tons of this and other 
costly metals. Above this core comes a vast layer of 
metallic iron. Probably about half the giant bulk of the 
earth consists of metallic iron. The raging white heat of a 
great iron smelting furnace is as nothing when compared to 
the temperatures reigning within the great furnaces of the 
earth's depths; there gleam vast masses of iron heated 

* " Zur Physik des Vulcanismus," Geol. Foren. i Stockholm For- 
hand. 22 (1900), pp. 395-419. " Das Werden der Welten " (Leip- 
zig, 1908), p. 1. 

To the list on previous page must be added Asterium and 
Nebulum, light elements unknown upon the earth, which occur in 
very hot stars and nebulae ; also Coronium, a light element occur- 
ring in the sun's corona. 

Note. — As originally defined the atomic weight of an element 
meant the number of times its atom outweighed the hydrogen atom, 
but, for various reasons, it is now found more convenient to fix the 
atomic weight of oxygen as 16 and that of hydrogen as 1.008, and 
express the weights of the other elementary atoms relative to 
Oxygen 16. 
c 



34 MODERN CHEMISTRY 

so strongly as to be in a gaseous state, yet compressed 
with such tremendous force as to be denser than solid steel. 
Of the whole 8,000 miles of the earth's diameter, no less than 
6,000 are supposed to consist of this gaseous iron sphere. 
This is followed by a layer, 600 miles thick, of gaseous rock- 
magma. Then comes a layer 160 miles thick of molten white- 
hot rock, and finally comes the solid crust on which we 
live and which cannot be more than 100 miles thick, 
and in most parts of the earth is much less than 30 miles 
thick. 

We have good reason to believe from many facts, astrono- 
mical and geological, that the bulk of our earth is iron. For 
example, the fragments of matter which wander through 
the waste spaces of the universe, and finally fall upon the 
earth as meteorites, usually consist of metallic iron 
mingled with small quantities of metals like calcium, 
nickel, cobalt, aluminium, and non-metals like sulphur, 
phosphorus, oxygen, carbon, and other materials or 
gases. Now meteorites are composed of dust collected 
from millions and millions of suns during millions and millions 
of years. From every sun and from almost every world in this 
vast universe of ours there escape yearly into space thousands 
of tons of dust particles. These particles are shot out from 
suns during the titanic explosions which are continually 
convulsing their surfaces ; from the colder worlds they are 
hurled forth into space amidst the thunder of volcanic 
explosions. Once these particles get free into space they 
are, according to Arrhenius, driven away from the suns 
into the deepest depths of the universe by the pressure of 
the light falling on them, the light pressure overbalancing 
the attractive force of gravitation when the mass of the 
particles falls below a certain value. In the waste spaces 
of the universe these tiny particles gravitate together and 
form, among other things, meteorites. Now since meteorites 
are formed from matter derived from the most various celes- 
tial bodies during almost an eternity of time, they must 
represent the average composition of celestial bodies. As 
meteorites are formed principally of iron it follows that the 
bulk of most celestial bodies is also metallic iron There is 



ELEMENTS— DISTRIBUTION AND EVOLUTION 35 



every reason for believing that our earth has the same 
composition as other celestial bodies, and that therefore 
it consists principally of metallic iron. 

Again, in Greenland there exist strewn over the surface 
of the land in the neighbourhood of Disco, great blocks of 
metallic iron, some of them weighing many tons ; and 




^ 



xxxxx 



Gaseous metallic sphere, principally iron, 6,000 miles in 

diameter. 



Gaseous rock magma, 600 miles thick. 
Molten white-hot rock, 160 miles thick. 



Outer solid crust of the earth, under 100 miles thick. 
Fig. 7. — Predominance of Iron in the Earth. 



there is reason to believe that these did not fall on the 
earth from the sky as meteorites, but rather came up with 
the lava which overflowed Greenland in some tremendous 
volcanic catastrophe ages ago. These blocks, therefore, 
represent some of the native iron in the earth which actually 
found itself carried to the surface of the planet by volcanic 



36 MODERN CHEMISTRY 

agency. Old volcanic rocks are always found to be impreg- 
nated with tiny particles of metallic iron which have 
apparently come up from below, and become entangled 
in the molten rock overlying the central iron core. 

The fact that the earth behaves as a big magnet also 
points to the existence of large amounts of iron in its 
interior.* 

A bright piece of iron left exposed to the air and damp 
soon turns brown, and after some time becomes entirely 
converted into a brown earth known as iron rust. The rust 
is merely a chemical compound formed by the iron uniting 
with an element in the air called oxygen. In just the same 
way part of the central mass of metals in the earth has ages 
ago combined with oxygen and other elements to produce 
the earthy crust which surrounds the earth and forms 
the land. Yes, the rocks, the hills, and the ground on which 
we tread are all more or less metallic rusts. Thus, the 
great hills and uplands of granite rocks are really chemical 
unions of metals with silicon and oxygen. In every ioo tons 
of these old rocks there are about 23 tons of bright shining 
metals like aluminium, iron, calcium, magnesium, potassium. 
The wonderful marble rocks, the chalk downs, and limestone 
peaks which cover thousands of miles of the earth's surface, 
are all composed of a beautiful silvery metal called calcium, 
combined with carbon and oxygen. Every 100 tons of 
marble or chalk contains nearly 40 tons of this metal. 
Whole mountain ranges are composed of a similar compound 
of the well-known element magnesium. 

We now come to consider the problem of the unequal 
distribution of the elements. Why are some of them 
scattered far and wide in such enormous masses throughout 
the whole universe, while others occur only in the minutest 
traces ? This question touches the deeper question of the 
origin of matter. Evidently we are dealing here with the 
handiwork of some vast cosmic law which has been operating 
over immeasurable intervals of space and time. 

Recent researches have thrown a flood of light upon these 
questions. It is now believed that the elements are not the 
* Arrhenius, " Das Werden der Welten," p. 17. 



ELEMENTS— DISTRIBUTION AND EVOLUTION 37 

changeless systems that they were once thought to be, but 
rather systems in slow but incessant mutation. 
^ According to Prof. J. J. Thomson, all the elements repre- 
sent successive condensations of one primary stuff, whose 
atoms, called " electrons " or " corpuscles/' weigh less than 
the one-thousandth part of an atom of the lightest known 
terrestrial element, namely, hydrogen. This primary stuff 
is negative electricity, which therefore is a true chemical 
element.* A flash of lightning consists of the swift rush of 
innumerable myriads of these negative electrical atoms, 
flying with the enormous speed of a hundred thousand miles 
and more a second. An electric current flowing along a 
wire consists likewise of a torrent of these particles flashing 
along between the atoms which make up the wire. Light is 
but the swift shudder in the ether set up by the rapid 
whirl of these negative electrons round their tiny orbits in 
the matter atoms. All the atoms of the elements consist of 
aggregations of many thousands of these bodies and origin- 
ated in very different quantities, as follows : 

In the beginning of time, long before Man, Earth, or Sun 
had come into existence, before even there was a suspicion 
of their formation, space was filled with a vast sea of electrical 
vapour. The vapour was composed not of atoms, for matter 
atoms had not yet come into existence, but of the tinier 
electrical particles mentioned above, the measureless speed 
of whose motions caused the whole to thrill with a faint 
crepuscular light, and appear from a great distance as a 
faintly luminous cloud, like one of the nebulae which gleam 
nightly at us down from the sky. 

The vapour, being composed of electrical atoms, was 
electrified beyond all measure, and stretched gleaming with 
its electrical fires, through the darkness of space like a flaming 
sword. It was the seat of inconceivable energy, of titanic 
forces, and, in Tennyson's words, our world and sun and the 
elements which build us up, took their birth 

* Sir William Ramsay, Trans. Chem. Soc, 1908, 93, 774. " Elec- 
trons are atoms of the chemical element electricity ; they possess 
mass ; they form compounds with other elements ; they are known 
in the free state, that is, as molecules." 



38 MODERN CHEMISTRY 

" From this great dtep, before our world begins. 
Where all that was to be in all that was 
Whirl'd for a million aeons thro' the vast 
Waste dawn of multitudinous eddying light." 

According to Prof. J. J. Thomson, the elements are 
supposed to have evolved from this fire-mist in the following 
manner : — 

The vapour was composed of particles both positively and 
negatively electrified. These attracted each other with 
very great forces, but the tremendous speed of their motions 
parted them even as they flashed by each other. Gradually, 
however, the particles radiated away energy in the form of 
light and heat, and, as a result, their motion became less and 
less swift until occasionally permanent connections were 
formed between them, and the first step in granulation 
took place. Thus the matter-atoms were formed as the 
price of the gleaming electrical light which the nebula sent 
forth ceaselessly. 

These first atoms consisted of only a few electrons grouped 
together, and were consequently much lighter than any 
elementary atoms now found upon the earth, the lightest 
of which consist of many thousands of electrons grouped 
together. Slowly during ages this aggregation of electrons 
continued, the atoms gradually growing and becoming more 
and more complex, until finally they consisted of aggrega- 
tions of over a thousand electrons, and formed the atoms 
of the element hydrogen ; the lightest atom known to us 
upon the earth is thus the end-product of a vast epoch of 
evolution. It represents the gradual condensation of over 
a thousand electrons. Before hydrogen there came a whole 
series of lighter elements which have long since vanished 
from our earth, having condensed into heavier elements. 
Astronomers say that in some nebulae, and even in the upper 
regions of the sun's vast atmosphere, such light unknown 
elements still gleam and glow. Many nebulae, indeed, 
are entirely composed of them. 

With the appearance of hydrogen the process of condensa- 
tion did not cease. All matter still continued passing in a 
stupendous scheme of slow continuous evolution from the 



ELEMENTS— DISTRIBUTION AND EVOLUTION 30 

lighter to the heavier forms. Yet for some time hydrogen 
was the only element in existence, and even now we often 
find nebulae and some very hot stars almost entirely com- 
posed of this gas. The amount of hydrogen thus found 
occasionally collected together in one region of space is 
almost inconceivably vast. The hydrogen in many a single 
star would out-weigh the vast mass of our earth a million 
times and more ! But hydrogen did not remain long the 
only element in existence ; the gradual accretion of electrical 
particles soon caused it to change into other and heavier 
elements. Elements like magnesium, calcium, iron, carbon, 
made their appearance, and at the same time the quantity 
of hydrogen diminished. Thus there was a practically 
continuous increase of atomic mass from the lightest to 
the heaviest known atom. 

A fairly consistent theory to account for the formation of 
the elements, founded on the researches of the Curies, 
Ramsay, Soddy, Rutherford, and others, has recently been 
put forward by A. C. and A. E. Jessup.* 
• According to these writers, in the earliest nebulae — the 
first stage of matter of which we have any knowledge — there 
exist only four elements, namely, two still unknown upon 
the earth, together with hydrogen and helium. These are 
the four elements from which all the others have formed, and 
these authors term them " protons " to distinguish them from 
the other elements. The electrons are supposed to condense 
about the atoms of these protons in the form of concentric 
rings ; so that in order to imagine the appearance of an 
atom, we must look upon it as composed of a series of 
rings of varying sizes, whose particles are in exceedingly 
rapid motion, and indeed, as we shall see presently, the 
stability of the rings is a consequence of the rapidity of the 
motion of the particles of which they are composed. This 
theory of atomic evolution explains the fact that all the 
elements are not met with in equal abundance. For the 
rate of accretion of mass is most rapid between positions of 
maximum stability as represented by our 70-80 elements. 
The intermediate forms in the upbuilding process of matter 
* Phil. Mag., January, 1908, p. 21. 



4 o MODERN CHEMISTRY 

have never accumulated in sufficient quantity to be detected 
by direct methods. The stable terrestrial elements represent 
only stages where the rate of change is slowest ; they are, 
so to speak, stopping-places in the process of evolution. 
And in general the more slowly an element changes into the 
next sort the more it will accumulate and tend to become 
abundant. Thus as the universe gets older and older 
elements of higher and higher atomic weights appear. Their 
appearance, however, will not involve the annihilation of 
the elements of lower atomic weights.* The number of 
atoms of the latter will, of course, diminish, since they go 
to furnish the material out of which the heavier elements 
are built up. But the whole of the light atoms will not be 
used up at once, and thus a large number of elements, both 
light and heavy, will exist simultaneously. The lighter ele- 
ments, however, must ultimately disappear, and unless there 
is a simultaneous disintegration of the heavier elements, 
the atomic weight of the lightest element surviving must 
increase. 

We may mention here that the formation of the successive 
elements is attended by the escape of large quantities of 
energy, and that the systems are steadily progressing from 
a higher to a lower energy content. The whole process of 
evolution is entirely governed by the possibility of energy 
leaving the system. — (Jessup, loc. cit. p. 24.) 

This slow, continuous transmutation of the elements, 
working for many ages, has probably produced stupendous 
effects upon the earth. The majority of light elements have 
already disappeared from it, the bulk of the interior being 
composed of heavy elements. Only on the surface there 
still lingers a thin skin of light elements, such as oxygen, 
nitrogen, carbon, hydrogen, silicon, — elements composing 
the bulk of the air, water, living matter, and rocks. If in 
the course of ages the light elements become converted 
entirely into heavy ones, which are usually metallic, the 
whole earth will become a vast metallic ball having the 
same composition as one of the iron meteorites which wander 
in space, and on which the same evolutionary forces have 

* J. J. Thomson, " Electricity and Matter " (Constable, 1904). 



ELEMENTS— DISTRIBUTION AND EVOLUTION 41 

already been working for ages. The green fields and the 
rich soft earth which now clothe our planet will vanish, and 
in their place will stretch a vast, hard, metallic desert, lifeless, 
waterless, airless, whirling silently in space towards an un- 
known destination. The merest glance at the sky through a 
telescope will show us that our world is only one of many 
worlds, a number of which must have long since reached such 
a stage of development. One can scarcely doubt, therefore, 
the general correctness of the poet Tennyson's conjecture 
that in the myriad-worlded universe about us 

" Many a planet by many a sun may roll 

With the dust of a vanished race, 

Swallowed in Vastness, lost in Silence, 

Drowned in the deeps of a meaningless Past." 

And that some day our own world will go to join them, for 

" Many an Aeon moulded Earth 

Before her highest, Man, was born. 
Many an Aeon, too, may pass when 
Earth is manless and forlorn/' 

" This is very interesting," I seem to hear my readers say, 
" but how do we know that it is true or even probable ? " 
It would take too much of our time and space to completely 
discuss the evidence in favour of these conclusions, and I 
cannot do better than refer the curious to the pages of 
Professor J. J. Thomson's books* where a full account will 
be found by one of the founders of the theory. Also a 
long series of difficult researches on the spectra of the stars, 
by Sir Norman Lockyer, affords confirmative evidence of 
the truth of this theory. Lockyerf shows that while the 
cooler stars consist principally of elements with heavy atoms, 
such as iron, calcium, manganese, and nickel, the hotter stars 
consist principally of elements with light atoms ; and if we 
arrange the stars in ascending order of temperature, the 
quantity of the heavier elements steadily diminishes as the 
temperature increases, and in proportion as they diminish 

* See " Electricity and Matter," by Thomson (Constable, 1904). 
" Recent Developments of Physical Science," by Whetham (Murray, 
1905). " The Interpretation of Radium," by Soddy (1910). 

t " Inorganic Evolution" (Macmillan, 1900). 



42 MODERN CHEMISTRY 



their place is taken by the lighter elements, until in the hot- 
test stars of all the heavy elements have completely vanished, 
such stars being completely composed of the lightest of all 
known elements, such as the gaseous hydrogen, helium, 
nebulium, and asterium. The inference is that the heavy 
atoms have under the reign of enormous temperatures 
broken down into lighter atoms. In Lockyer's words : 

" In the very hottest stars we deal, speaking generally, with the 
gases hydrogen, helium, asterium, and doubtless others still unknown, 
almost exclusively. At the next lowest temperatures we find these 
gases being replaced by metals in the state in which they are observed 
in our laboratories when the most powerful arc-spark is employed. 
At a lower temperature still the gases almost disappear entirely and 
the metals exist in the state produced by the electric arc. . . take 
iron as an example. . . it will be seen . . . that as the temperature 
increases hydrogen increases, and, together with the cleveite gases 
not obvious before, finally replaces the iron which has disappeared. 
This is one of the great stellar revelations, and it must be remembered 
that we have now hundreds of photographs which we can bring to- 
gether to study the gradual change. There are no ' breaks in strata.' 
One of the most wonderful things about this line of work to my mind 
is the simplicity, coupled with the continuity of the phenomena. . . it 
carries conviction with it. We have then to face the fact that on 
the dissociation hypothesis, as the metals which exist at the tempera- 
ture of the arc are broken up into finer forms, which I have termed 
proto-metals, at the fourth stage of heat (that of the high-tension 
electric spark) which gives us the enhanced spectrum ; so the proto- 
metals are themselves broken up at some temperature which we 
cannot reach in our laboratories into some other simpler gaseous 
forms, the cleveite gases, oxygen, nitrogen, and carbon being among 
them. 

" Does the story end here ? No, there is still a higher stage ; after 
the cleveite gases have disappeared as the arc lines and enhanced 
lines did at the lower stages, the new form of hydrogen to which I 
have before called attention, and which we may think of as ' proto- 
hydrogen,' makes its appearance. But there are already evidences 
that this is not the end of the simplifications brought about by the 
transcendental temperatures we are now discussing."* 

In this manner f each nebula and each sun must be regarded 
as swiftly weaving the vast fabric of the universe at the loom 

* Quoted by kind permission of Macmillan & Co. from Lockyer's 
" Inorganic Evolution," pp. 56 and 81. 

f Some chemists of great ability do not accept Lockyer's conclusions. 
Arrhenius, for example, believes that the fact that nebulae are com- 
posed of light elements like hydrogen, helium, nebulium, etc., can 






ELEMENTS— DISTRIBUTION AND EVOLUTION 43 

of time. They are, in fact, the great chemical workshops 
of the universe in which the elements are forged and fashioned. 
In them and on a stupendous scale, often at temperatures 
and pressures so vast as to be almost inconceivable to us, 
the different kinds of atoms are conceived and born ; and 
from these atoms the whole order of creation magnificently 
evolves, sun by sun, world by world, beast by beast, plant 
by plant, down to the minutest microscopic animalculae 
swimming in a drop of water. We must, therefore, now 
say a few words about these vast stellar laboratories. 
\JrIow huge some of the nebulae are may be gathered from 
the fact that one* of them alone, and that one not the largest 
by any means, covers an area in the sky about five times that 
of the full moon, and yet is such a vast distance away as 
to be practically immeasurable by our most refined and 
delicate instruments. A minimum estimate of its distance 
from the sun shows that it must have a diameter at least 
500,000 times the sun's distance from the earth ! Light at 
the velocity of 186,000 miles a second would take more than 
eight years to pass from one side to the other of this vast 
nebula ! and yet light moves so quickly that in a single 
second it will flash 200 times from London to Edinburgh 
and back again. A better idea, perhaps, of the size of this 
nebula may be obtained by supposing that a railway were 
laid across it, and that a train starting on its long journey 
over this railway was not to stop until it reached the other 
side of the nebula. Suppose the train went off with the 
speed of a mile a minute ; then it would travel on 
hour after hour until slowly the hours would lengthen 
into days, and the days would creep into years, 
the years would swell into centuries, and still the train 
would rush on, day and night, century after century, for 

be explained by assuming that under the great cold reigning in such 
regions of space, all except the lightest elements have condensed 
to a liquid or solid state, and have gravitated together into the interior 
regions of the nebula. The shell of gas existing on the edges of the 
nebulae is then rendered luminous, and so apparent to us, by dust 
particles and electrons flying into it from space. — (Arrhenius, "Das 
Werden der Welten," p. 176.) 

* The nebula in Argo, see Gore's " Worlds of Space," Chapter 20. 



44 MODERN CHEMISTRY 

thousands and tens of thousands and hundreds of thousands 
of years until a million years had passed. And even now the 
nebula is not nearly crossed ; for the train has barely passed 
the hundredth part of its journey along the mighty track ! 
Not until the train had rushed on at the unabated speed oi 
a mile a minute for ninety million years would the terminus 
at the other side of the nebula be reached ! It is highly 
probable that even then it would not be reached, no, not 
for aeons of ages afterwards, for our estimate of the size of 
the nebula is, remember, a minimum one. This is only 
one nebula out of thousands upon thousands which can be 
seen in the sky by means of a small telescope ! 

That strange unknown changes are going on in these 
vast gaseous mists is admitted by all who have studied them. 
"The astronomer finds it difficult," says Simon New- 
comb* " to conceive that the great nebulous masses which 
he sees in the celestial spaces — millions of times larger 
than the whole solar system, yet so tenuous that they offer 
not the slightest obstruction to the passage of a ray of light 
through their whole length — situated in a region of what 
seems to be eternal cold, below anything that we can produce 
on the earth's surface, yet radiating light, and with it heat, 
like an incandescent body — can be made up of the same kind 
of substance that we have around us on the earth's surface. 
Who knows but that the radiant property that Becquerel 
has found in certain forms of matter may be a residuum of 
some original form of energy which is inherent in great 
cosmical masses, and has fed our sun during all the ages 
required by the geologist for the structure of the earth's 
crusts ? It may be that in this phenomenon we have the 
key to the great riddle of the universe, with which profounder 
secrets of matter than any we have penetrated will be opened 
to the eyes of our successors. . . Astronomical and 
physical research are now being united in a way which is now 
bringing the infinitely great and the infinitely small into one 
field of knowledge. Ten years ago the atoms of matter, of 
which it takes millions of millions to make a drop of water, 

* "Side-lights on Astronomy" (1906), pp.21, 59, by kind per- 
mission of Harper and Brothers, the publishers. 



ELEMENTS— DISTRIBUTION AND EVOLUTION 45 

were the minutest objects with which science could imagine 
itself to be concerned. Now a body of experimentalists, prom- 
'nent among whom stand Professors J. J. Thomson, Becquerel, 
a.nd Rontgen, have demonstrated the existence of objects 
so minute that they find their way among the atoms of 
matter as raindrops do among the buildings of a city. More 
wonderful yet, it seems likely, though it has not been 
demonstrated, that these little things, called ' corpuscles,' 
play an important part in what is going on among the stars. 
Whether this be true or not, it is certain that there do 
exist in the universe emanations of some sort, producing 
visible effects, the investigation of which the nineteenth 
century has had to bequeath to the twentieth." 

If strange changes take place in the nebulae, still stranger 
take place in many of the giant suns of space. Here chemical 
changes progress night and day, century after century, 
under conditions quite unparalleled and unparallelable 
in our earthly laboratories. For down in the depths of 
these giant bodies is a heat immeasurably fiercer than any 
heat we know upon this earth, and a pressure immeasurably 
vaster than any pressure that we can imagine. 

Some idea of the magnitudes of these stellar temperatures 
may be obtained by considering the case of our sun, a rela- 
tively cool body in comparison with some of the suns of 
space. Yet its surface actually attains the prodigious 
temperature of 6,200 C, a temperature high enough to boil 
steel like water and to instantly convert the most involatile 
substances known upon the earth into a mass of white-hot 
vapour. Lockyer estimates that the surface temperature of 
some suns is at least 30,000 C. ! for certain stars radiate 
out, surface area for surface area, a vastly greater amount 
of heat and light than does our sun. But even these surface 
temperatures, great as they seem to us, are quite insignifi- 
cant when compared with those prevailing hundreds of 
thousands of miles in the depths of these vast globes. Arr- 
henius speaks of a temperature of 71,000,000° C. Incred- 
ible ! you will say. Not a bit of it. For we have seen in 
our first chapter that matter cannot travel faster than light, 
and therefore the highest temperature attainable by any 



46 MODERN CHEMISTRY 

substance will be reached when its molecules travel with the 
velocity of light, that is, at the rate of 186,000 miles a second. 
Now it can be calculated easily that when the molecules of 
hydrogen attain this unheard-of speed the gas will be at the 
enormous temperature of between six and seven million 
million degrees centigrade. Such hydrogen would be a 
hundred thousand times hotter than a star at the temperature 
mentioned by Arrhenius ! Indeed we know that on the 
sun vapours are hurled about with a speed of over 500 miles 
a second. If the molecules themselves which make up such 
vapours possess anything like these average speeds the 
mean temperature of the vapour itself must amount to 
several million degrees centigrade. 

We can realise easily a degree of heat expressed by the 
temperature of boiling water ; we can even realise, but with 
some difficulty, a degree of heat half-a-dozen times hotter 
than this, for example, that of molten iron ; * but when we 
come to deal with temperatures two hundred thousand 
times hotter than boiling water, our imagination fails us 
altogether. Now, if a temperature merely 5 to 6 times hotter 
than boiling water produces such a great difference in the 
properties of matter as that which exists between the water 
boiling in our kettles, and the gleaming, dazzling, white-hot 
molten iron, seen as it pours from the great blast-furnaces 
of iron works, we may well dimly wonder what would be the 
effect of a vast stellar temperature 200,000 times hotter ! 
How puny in the face of these tremendous natural temper- 
atures appears the greatest intensity of heat ever produced 
on the earth by man — that of 7000 C. in the electrical 
furnace ! Is it a wonder that on such stars in their mighty 
depths chemical changes absolutely unrealisable in our 
earthly laboratories proceed with the greatest ease ? 

The words of the dying Victor Meyer rang prophetically 
in the ears of the chemists of his time : " There can be no 
doubt,' ' he said, " that new and undreamed of discoveries 
will manifest themselves, that a new chemistry will disclose 

* Water boils at 373 Absolute (ioo° C), iron melts at 1873 
Absolute (1600 C). Hence molten iron is about five times hotter 
than boiling water. 



ELEMENTS— DISTRIBUTION AND EVOLUTION 47 

itself, when we are furnished with vessels that will enable 
us to work at temperatures at which water no longer exists, 
and at which the oxy-hydrogen blowpipe flame becomes a 
non-inflammable mixture." Science is rapidly approaching 
the time when Meyer's dream may perhaps be realised. 

Enormous as these stellar temperatures may seem, they 
are more than paralleled by the stellar pressures. The 
pressure at the centre of the earth has been estimated at 
three million atmospheres, or, 20,000 tons per square inch.* 
Now the earth is a mere speck in comparison with the sun. 
The sun outweighs the earth three hundred thousand times ! 
Their relative size is expressed by that of a grain of fine 
shot and a full sized football, or a marble and a full sized 
living room. The diameter of the sun is 866,400 miles, 
nearly a hundred times that of the earth (9,718 miles), while 
its volume is 1,395,000 times that of the earth. " If a million 
globes," says Sir Robert Ball, " as large as our earth could 
be united together, no doubt a vast globe would be produced, 
but it would not be so large as the sun. Think of a single 
house with three or four people living in it, and then think 
of this mighty London, with its millions of inhabitants. 
The house represents the earth, while great London repre- 
sents the sun ! " Now if the pressure 4000 miles down 
in the interior of the earth is of the order of 20,000 tons 
per square inch, what would be the pressure at the sun's 
centre at the vast depth of 400,000 miles ? It would 
seem that there certainly exist suns in space far vaster than 
our sun. Thus, the star Mizar, the middle star in the tail 
of the Great Bear, is a double sun weighing forty times 
as much as our sun. This is quite a small body com- 
pared with such giant suns as Capella, Arcturus, Canopus, 
and Rigel, bodies so far off that their distance is immeasur- 
able by the most refined instrumental means known to 
astronomy, and yet emitting light with such power as to 
appear the brightest stars in the heavens. According to 
Newcombf the actual amount of light emitted by Canopus 

* Geikie's " Text-Book of Geology " (4th edition, 1903), p. 59, 
Vol. I. 

f " Side-lights on Astronomy," p. 397. 



48 MODERN CHEMISTRY 

and Kigel is certainly thousands, and probably hundreds of 
thousands of times that emitted by our sun. Such 
bodies must be extraordinarily massive, probably entirely 
dwarfing our sun, vast as he seems to us. This is confirmed 
by measurements made on other stars. Listen for example 
to what Gore* says about Arcturus : — 

" A minute parallax of about one-sixteenth of a second of arc, 
found for Arcturus by Dr. Elkin, gives a still more astounding result. 
This small parallax implies a distance from the earth of about twelve 
millions times the sun's distance. . . . The sun placed at the distance 
of Arcturus would be reduced to a star of only gf magnitude. It 
would not be visible in an opera glass ! Arcturus is therefore . . . 
over 6000 times brighter than the sun would be if placed at the same 
distance. Assuming the same density and brightness as the sun, the 
diameter of Arcturus would, therefore, be about 79 times the sun's 
diameter, or over 68,000,000 miles, and its mass about 500,000 times 
the mass of the sun ; figures well calculated to ' stagger the imagina- 
tion.' From the small value of the parallax found for Arcturus, we 
cannot, of course, place very much reliance on its accuracy ; but 
there can be little doubt that this bright star is really very great, and 
that consequently it is a much larger sun than ours, probably one of 
the most massive bodies in the uni verse.' ' 

In the depths of such giant bodies the pressures may 
amount to millions, perhaps billions, of tons on the square 
inch. It is, indeed, difficult to imagine such tremendous 
pressures. At a pressure less than two hundred tons on the 
square inch the strongest steel will flow like mobile water, 
and the solid condition of matter loses all meaning. We 
can only speculate as to how matter will behave when sub- 
jected to these vast stellar pressures. 

Equally extraordinary are the titanic forces which hurl 
matter about over the surfaces of these fiery globes. On 
them explosions occur a thousand times more violent than 
the mightiest dynamite explosion ever known. White hot 
winds rush over their surface a thousand times swifter than 
a rifle bullet, winds which would shatter and tear to pieces 
in an instant of time our whole earth, vast as it seems to us. 
We are quite unable to realise such conditions. And yet 
these are the normal conditions under which chemical 

* Gore, " Worlds of Space," pp. 74-75, by kind permission of the 
Author. 



ELEMENTS— DISTRIBUTION AND EVOLUTION 49 

change goes forward in the universe. It seems quite impos- 
sible to attain in our earthly laboratories the means to 
imitate chemical changes which require such enormous tem- 
peratures and pressures, changes such as the breakdown of one 
element into the other, which seems to progress with such 
ease in the stars, and the unlocking of the titanic energies 
stored up in the atoms. For our whole world is but a tiny 
atom flying in a sea of giant suns. It is itself but a tiny 
product of the vaster stellar laboratories. It is clear, there- 
fore, that human chemistry must, after all, be a very one- 
sided affair. It is as a rule only concerned with chemical 
changes which take place under conditions of temperature 
and pressure not greatly different from those under which 
we live and work. Our chemistry is, in fact, just one chance 
section through the vast organism of chemical facts. What 
wonders would be revealed if we could only take other sec- 
tions at vastly different temperatures and pressures, and thus 
enter into the great unknown chemical world which exists 
under physical conditions totally different from those we 
are acquainted with, will probably remain for ever veiled 
from the intellect of man. The wonder is not that we know 
so little but that we know so much. 

For in Tillman's words,* "Above and below the narrow 
zone of the visible are objects too far off and too fine for 
human scrutiny. Although the ' seeming all ' is rounded by 
intimations of other and brighter regions, Science can never 
compass them by any extension of her domain. In those 
unsounded depths which form the boundary and the back- 
ground of the known, thought, grown dizzy, finds no support." 

Tennyson has expressed the same idea in grand and beauti- 
ful language in his " Ancient Sage " in the well-known lines : 

f ' For Knowledge is the swallow on the lake 
That sees and stirs the surface shadow there 
But never yet hath dipt into the abysm, 
The abysm of all abysms, beneath, within, 
The blue of sky and sea, the green of earth. 
And in the million-millionth of a grain 
Which cleft again for evermore, 
And ever vanishing, never vanishes." 

* " Nature," 1872, 



I 



50 MODERN CHEMISTRY 

We have seen that in the heavens before our eyes there is 
taking place a swift and ceaseless formation of heavier from 
lighter elements by a process analogous to condensation ; 
but the reverse process is certainly taking place in parts of 
the earth ; for elements have been recently discovered which 
are undoubtedly breaking down into lighter elements ; 
thus the element radium appears to give rise to helium, 
the light gas which exists in so many stars. It has recently 
been shown that changes of a similar nature are going forward 
slowly, in many elements, especially in thorium, uranium, 
and the alkali metals. Such elements are known as " radio- 
active," on account of peculiar rays which they send out. 
We will later devote some space to the radio-active 
elements, and so it must suffice to say that if in certain regions 
of the universe matter is condensing to heavier and heavier 
elements, it is equally certain that in other regions the heavy 
elements are again breaking up into lighter forms of matter. 
In other words the atoms can be split up into their dust or 
primary matter, in the same way that comets break up into 
meteorites, and just as the geological changes of the earth or 
the building up and dissociation of heavenly bodies proceed 
incessantly before us, " so also do the atoms break up and 
form again in the silence of their eternal evolution." 

There is nothing surprising in this. The chemical atoms 
grow out of a fine ultra-atomic gas, in the same way that 
visible raindrops grow out of invisible aqueous vapour ; 
and the atoms dissolve again into this ultra-atomic mist, 
just as raindrops evaporate away again into invisible aqueous 
vapour. There is thus going on a continual mighty change 
in matter, slow to our eyes but inconceivably swift when 
measured by the standard of eternal time Now just as 
a planetary system will collapse if the velocity of the planets 
falls below a certain value — the planets then rushing into 
the central sun round which they revolve — so also in the 
atoms, if the velocity of rotation of the electrons becomes 
reduced below a certain critical value, a stable configuration 
of rotating electrons will become unstable and the atomic 
planetary system collapses with a crash. When this occurs 
the tiny fragments fly in all directions, some being shot out 






ELEMENTS— DISTRIBUTION AND EVOLUTION 51 

with a velocity of a hundred thousand miles a second ! 
The residue of whirling corpuscles again group themselves 
into another configuration which is stable under the altered 
conditions. A new element is thus formed. After some 
time this, losing energy, becomes unstable and in its turn 
forms another atomic species with the loss of some more 
electrons. 

These changes have been most carefully studied in the 
case of the newly discovered element radium, which breaks 
down into several products, among which is the light element 
helium. Each change is usually attended with the evolu- 
tion of electrons, and proceeds so rapidly that according to 
Rutherford* half a given mass of it is destroyed every 
1.300 years. It has recently been shown that almost 
all the elements eject corpuscles, after the manner of 
radium, and hence are probably undergoing a very slow 
decomposition. 

~ The amount of energy set free by the decomposition of 
these atomic systems is incredibly vast. Thomson has calcu- 
lated that if the energy in the atoms of one gram (i.e., 15J 
grains) of hydrogen was liberated it would be able to lift 
a million tons to a height considerably greater than a hundred 
yards ! 

- One ton of radium in decomposing gives out enough heat 
in one hour to raise the temperature of one ton of water 
to its boiling point. Hour after hour, year after year, it 
continues to do this, and would continue to do so until, 
some thousands of years hence, it had exhausted its store 
of energy. And thus it is that men came to realise that 
within the very atoms of matter there exists such incalcul- 
ably vast funds of energy that the sum total of all the energies 
previously recognised, and now called extra-atomic, are as 
nothing compared to them. " This is a change, indeed," says 
Dr. Saleeby, " that all the energies hitherto known to us 
should be merely the overflow trickling from the im- 
measurable ocean of intra-atomic energy." f 

Before the advent of radium the whole universe was 

* Rutherford, " Radio-activity " (Cambridge, 1905), p. 450, 
t " Karmswortk's History of the World," Vol I. 



52 MODERN CHEMISTRY 

supposed to be hastening into a state of death.* Universal 
gravitation was supposed to be slowly collecting together all 
matter into one great heap, and outside of the aggregation 
of suns which form our universe there existed nothing but 
empty space extending for all infinity. All the suns which 
thus form our limited universe were known to be radiating 
away their heat and light, and thus all must cool and the 
universe must end in the death of an everlasting cold and 
night. This comfortless doctrine did not appeal to every 
one. The great thinker, Herbert Spencer, asserted that 
there must be some unknown forces at work which opposed 
the obvious tendency of matter to aggregate into a state of 
death. There must be disintegration going on as well as 
integration. He believed that the universe was eternal ; 
that it had always existed and always would exist in a state 
of never-ending change. 

Spencer was ridiculed by many eminent physicists, and 
at his death one of the greatest thinkers that England has ever 
produced was not thought worthy of a burial place in West- 
minster Abbey. Recent discoveries, however, seem to 
indicate that Spencer was considerably nearer the mark than 
his antagonists. Radium shows that there is going on a 
continual breakdown of integrated matter into lighter forms, 
while astronomical observations indicate that at the same 
time there is going on an upbuilding of heavy from light 
elements. Thus apparently there is going on in Spencer's 
sense a continual circulation of matter in the universe, a vast 
cycle of change from light to heavy and heavy to light. 

It is true that the formation ol heavy from light elements 
in incandescent masses of matter like the stars is probably a 
comparatively speaking, rapid process, while the break down 
of integrated into disintegrated matter, as it occurs on our 
earth, and in other cold non-luminous masses of matter, 
is probably a fairly slow process. A single pound of our 
ordinaiy matter will probably exist for many billions of 
years. Yet when we come to consider that the mass of 
dark invisible matter in the universe probably is a million 
times greater than the quantity of incandescent matter, 
the slower rate of disintegration of the cold matter is com- 



ELEMENTS— DISTRIBUTION AND EVOLUTION 53 

pensated by the very great masses of matter thus simul- 
taneously disintegrating ; and thus the rate of formation and 
the rate of disintegration in the long run balance each other. 

We have still to face the problem of the continual radia- 
tion of heat and light into space. This has always seemed 
a great waste to many scientists, who could hardly bring 
themselves to believe that it was really lost. This objection 
has been well put by Newcomb. " What," says he, " becomes 
of the great flood of heat and light which the stars radiate 
into empty space with a velocity of one hundred and eighty 
thousand miles a second ? Only a very small fraction of this 
can be received by the planets or by other stars, because these 
are mere points compared with their distance from us. 
Taking the teachings of our science just as it stands, we should 
say that all this heat continued to move on through infinite 
space for ever. In a few thousand years it reaches the con- 
fines of our great universe. But we know of no reason why 
it should stop here. During the hundreds of millions of 
years since all our stars began to shine, has the first ray of 
light and heat kept on through space at the rate of one 
hundred and eighty thousand miles a second, and will it 
continue to go on for ages to come ? If so, think of its 
distance now, and think of it still going on to be forevei 
wasted ! Rather say that the problem what becomes of 
it is as yet unsolved." 

Now it has been shown recently that radiant light and heat 
exert a pressure on very light particles of matter, repelling 
them into the depths of space, away from the great suns 
which give out heat and light. These dust particles gradually 
accumulate in the depths of the universe away from large 
masses of matter, and form vast nebulae, which after ages 
condense to suns and worlds again. Thus the light and heat 
is not wasted, it is all caught in the infinite depths of space 
by innumerable grains of dust, and thus forms an important 
part in the formation of new worlds. These worlds ultimately 
collide with the dark, cold, burnt-out suns, which rush, 
apparently so aimlessly, through space, and by the appalling 
force of the collision again reproduce nebulae, which again 
condense to worlds And so on for all the ages circulates 



54 MODERN CHEMISTRY 

the universe, like some vast self-compensating machine, 
radiation pressure compensating gravitation, and the 
concentration of potential heat energy in the nebube com- 
pensating its loss in the suns. Thus, although the earth will 
pass away, and with it Man and the very elements of which he 
is composed, we have no reason to believe that the universe 
itself will ever end by sinking into that state of death fore- 
told by the physicists of the last century. The proba- 
bilities are that life exists and always will exist generally 
disseminated through it wherever the conditions are favour- 
able ; and that although life may come to an . end in one 
planet yet there are always other planets where it can 
continue to flourish.* 

All this has been expressed by Sir Lewis Morris in the 
following beautiful words : 

" Undying is each cosmic force : 
Undying, but transformed, it runs its endless course. 
It cannot wane, or sink, or be no more. 
Not even the dust and lime which clothe us round 
Lose their own substance in the charnel ground, 
Or carried far upon the weltering wind ; 
Only with other growths combined, 
In some new whole they are for ever— 
They are and perish never. 

The great suns shed themselves in heat and light 
On the vast vacant interstellar air, 
Till when their scattered elements unite 
They are replenished as before they were. 
Nothing is lost, nor can be : change alone, 
Unceasing, neverdone, 

Shapes all the forms of things, and keeps them still 
Obedient to the Unknown Perfect WiUV'f 

* A full discussion on the possibility of life existing on other 
planets under physical conditions widely different from those now 
holding on the earth will be found in the author's work, " Researches 
on the Affinities of the Elements " (Churchill, 1905), Appendix B, 
pp. 245-257. 

Arrhenius (" Das Werden der Welten," Chapter 7) discusses the 
possibility of germs of life being driven from world to world by 
means of the repelling force of radiation pressure. 

t By permission of Kegan Paul, Trench, Triibner & Co., from " The 
Wanderer." 



CHAPTER IV 

THE WONDERS OF CHEMICAL CHANGE 

The importance of chemical change to mankind can scarcely 
be realised by any one not acquainted with chemistry. The 
fires which burn in our grates and supply us with warmth 
and light during the cold and gloomy winter months, the 
explosion which hurls a bullet with irresistible force from 
a rifle barrel, or which blasts up great rocks in our quarries, 
the power which drives our locomotives and steamships 
far over land and sea, are all due to chemical changes. The 
simplest as well as the most complicated changes which 
accompany life are, to a great extent, chemical in character. 
We cannot cook our dinner, nor digest it when cooked, we 
cannot move, laugh, or talk except by the direct operation 
of chemical changes. Even the very thoughts which flash 
so quickly through our minds, and the passions which stir 
us to love or hate, are inseparately connected with chemical 
changes that take place in our brains. In order to be con- 
vinced that vital changes are closely connected with chemi- 
cal phenomena, we need only to observe that the higher 
breathing animals resemble the burning candle not only in 
producing the same products of combustion, viz. — water 
and carbon dioxide, but also in the heat they produce ; 
for animals, like flames, are hotter than the surrounding air, 
and the difference between them is one of degree only. In 
the candle the oxidation goes on quickly and is confined to 
one spot — the wick, whereas in the case of an animal oxida- 
tion goes on slowly and takes place throughout the body. 
The poet who first compared life to a flame was nearer the 
truth than perchance he imagined. 

We have not yet explained what we mean by a chemical 
change. A chemical change is brought about by atoms of 
different sorts rushing together, or " combining," as a 

w 



56 MODERN CHEMISTRY 

chemist would say, to produce new substances. Thus, if 
powdered sulphur and fine copper filings are well mixed, 
a green-coloured powder results, in which, however, a micros- 
cope will show the particles of sulphur lying by the side of 
the particles of copper. On gently warming this green powder 
it suddenly bursts into bright incandescence, and, on cooling, 
a uniform black mass is produced. This is neither copper 
nor sulphur, but a chemical compound of the two, in which 
no particles of either of the substances can be seen, no matter 
how high a magnifying power be employed, but from which, 
by the employment of suitable chemical means, both copper 
and sulphur can be extracted. What has happened ? The 
atoms of copper and sulphur have combined, causing while 
so doing such an atomic agitation that heat and light are 
evolved, and as a result a body is produced quite different 
from either copper or sulphur, yet composed of atoms of 
sulphur and copper united. 

A scene from a ball-room will illustrate this rearrangement 
of atoms. At one end of the brilliantly lighted hall stand 
a number of men, confusedly grouped together and talking. 
We take them as representing the copper atoms before union. 
Similarly at the other end of the room is a group of gaily 
dressed and animated ladies. These we take as represent- 
ing the sulphur atoms. Though occasionally a man moves 
or a girl laughs there is little movement among the mass 
of people, and the whole scene corresponds to the, compara- 
tively speaking, quiescent mixture of sulphur and copper 
atoms before chemical union. Suddenly the music commences 
for a dance. All is instantly in a state of motion. The men 
come hurrying up to the ladies, each bent on securing a 
partner, and in a few seconds the whole assembly rearranges 
itself and goes dancing away in pairs. The confused rush 
of the men for the women corresponds to the moment of 
chemical union of our copper and sulphur atoms ; the 
increased motion stirring in the people at this time repre- 
senting the rapid molecular agitation attending chemical 
union, which usually manifests itself as heat and light. 
Finally the new arrangement of the assembly into pairs, 
each consisting of a man and woman, corresponds to the 






THE WONDERS OF CHEMICAL CHANGE 57 

new arrangement of the copper and sulphur atoms in the 
black copper sulphide produced as the result of chemical 
combination. 

What occurs in this reaction between copper and sulphur 
is typical of chemical change in general. In each case we 
get a set of atoms uniting or separating, and the moment 
of union or separation is marked by a thermal disturbance 
of some sort, this thermal disturbance taking the form some- 
times of a sudden evolution of heat and light, but some- 
times of an absorption of heat ; but in all cases of chemical 
union the products of the change differ entirely in appearance 
and properties from the bodies producing them. 

Naturally the question which next presents itself to the 
mind of the reader is this : What causes the atoms to unite ? 
The answer to this question is that the atoms unite in conse- 
quence of attractive forces they exert on each other. These 
forces, however, cannot be due to the same gravitational force 
that urge planets and suns together. They are far too vast 
for that. The chemical forces of the atoms exceed the gravi- 
tational forces which such small masses exert, not millions 
but billions of times, as Helmholtz showed many years ago. 
Besides, the chemical forces are selective, while gravitational 
forces are not. The atoms, in fact, are dreadful snobs and 
are most particular with whom they associate. For example, 
fluorine atoms have a great attraction for hydrogen atoms 
and combine with them at ordinary temperatures so fiercely 
as to produce flame and even explosion ; but these fluorine 
atoms will have nothing whatever to do with oxygen atoms, 
which are much more chemically active than hydrogen 
atoms. They cannot be made to combine with them at all. 
The same sort of thing occurs with the atoms of all the eighty 
odd known elements ; but little is known at present regarding 
the mutual attraction of the atoms for each other, and no 
doubt in this field many of the greatest discoveries of the 
future will be made.* The subject, in fact, is in its infancy. 

* The reader will find collected together nearly all that is known 
regarding the mutual attractions of the atoms for each other in the 
author's work, " Researches on the Affinities of the Elements and 
on the Causes which determine the Chemical Similarity of Elements 
and Compounds " (Churchill, 1905), 



58 MODERN CHEMISTRY 

A 

The idea which prevails at present in the minds of chemists 

and physicists is that these chemical forces are due in 
some way to electrical charges associated with the atoms. 
Certainly the incredible vastness of some of these chemical 
forces is well explained by this assumption. For example, 
d'Albe* calculates that two grams of pure negative elec- 
tricity placed side by side at a distance of one centimetre 
will repel each other with a force of over 320 quadrillion 
tons ! Even if they were placed one at the North Pole and 
the other at the South Pole of the earth, they would still 
repel each other with a force of 192 million tons, and this 
in spite of the fact that the force decreases with the square 
of the distance. So that a very small electrical charge 
associated with each atom would be sufficient to account 
for the chemical forces it exerts. The reader, however, 
must be warned not to accept blindly as true this view, as 
there exist many phenomena attending chemical combina- 
tion which are hard to explain on the assumption that the 
chemical attractive forces are entirely electrical in origin. 
v -s The best method of realising the magnitude of these 
chemical forces is by means of experiment. If the two 
invisible gases, hydrogen and oxygen, be mixed in a strong 
glass bottle in the ratio of two volumes of the former to one of 
the latter, and the mixture be brought near a flame, a bright 
flash of light and a deafening explosion announces to 
us that chemical union has taken place. What has been the 
occasion of the development of such tremendous energy ? 
The formation of a single drop of water, so small that one can 
hold it on the point of a needle ! Water, in fact, is formed by 
the chemical union of 1800 times its volume of these two 
gases. And the amount of energy produced in the formation 
of a single pound of it is adequate to raise 5,300,000 pounds 
one foot high, or hurl a man of average weight into the air to 
the height of over seven miles ! Who would have believed 
that such power was concealed in the familiar liquid so 
intimately connected with our daily life ? 

The reason why both heat and light are produced by this 
union of hydrogen and oxygen to form water, whose mole- 
* " The Electron Theory," by Fournier d'Albe (1906), 



THE WONDERS OF CHEMICAL CHANGE 59 

cules are composed of two atoms of hydrogen united with 
one atom of oxygen, is well worthy of a little further 
consideration. 

Suppose we place an oxygen atom at a small distance from 
a pair of hydrogen atoms and let us imagine that the atoms 
are in a fit condition for reacting chemically. These atoms 
exert mighty chemical forces on each other and instantly 
begin to rush together. The closer they get the more power- 
ful become the attractive forces and the swifter the atoms 
fly until they meet with an immense velocity, usually not 
directly colliding but grazing each other like comets grazing 
the sun. The final velocities with which the hydrogen atoms 
meet the oxygen atoms are often over four miles a second ! 
The atoms then commence to revolve one round the other 
and thus a molecule of water is born. Of course the impulse 
of the rush carries the atoms far beyond their mean position 
of equilibrium, and consequently violent surgings backwards 
and forwards — like the swingings of a pendulum — occur 
in the tiny new-born molecular system. Since millions upon 
millions of atoms of oxygen thus unite simultaneously in 
this way with twice their number of hydrogen atoms, it is 
obvious that the previously slow-moving mixture of mole- 
cules suddenly becomes converted into a mass of swiftly 
moving molecules. In consequence of this the temperature 
of the gas becomes enormously raised, because the tempera- 
ture of a gas depends upon the velocity of the molecules 
which compose it, increasing, indeed, with the square of the 
mean gaseous velocity. So that if we double the speed of 
the molecules we raise its absolute temperature to four times 
its previous value. In the case of a mixture of hydrogen 
and oxygen the temperature may, by the act of union, be 
raised in a few seconds from o° C. to over 2,000° C. ! 

We can thus understand easily the generation of a very 
large amount of heat by means of chemical combination, 
but something more is required to explain the light. For 
heat alone will not make a gas luminous. Some of the hot- 
test gaseous flames are non-luminous and almost invisible, 
while in some chemical reactions in which the heating effect 
is small the radiation of light is often very powerful. The 



60 MODERN CHEMISTRY 

evolution of light in a chemical reaction is now thought to 
be due to some process such as that we describe below. 

As we have already explained in our first chapter, light 
merely consists of the rapid quiverings of a material called 
ether which fills all space. These quiverings are caused by 
the rapid rushing to and fro around their orbits in the matter 
atoms of tiny electric particles called electrons, which revolve 
like so many little moons around the atoms. Now, as the 
molecules rush together in the act of chemical combination 
the electrons on the atoms themselves are violently agitated 
by the rising and falling attractions of the atoms as 
they rush past, and are thus set swinging or oscillating 
violently, so violently, indeed, that we have reason to believe 
that they sometimes fly off clear from the atom that they 
were accompanying on its journey through space. Thus 
the collisions with the atoms of other molecules enormously 
increases the energy with which the electrons revolve 
around the atoms, and causes each combining atom to become 
the centre of these tiny quiverings called light. Millions 
of atoms in the act of chemically combining each send 
forth its tiny flash of light, and the united gleam thus 
produced appears to us as a lightning flash of flame. What 
unthinkable complexity thus resides in a flame ! In the 
millionth part of a second the electrons must have flashed 
between one and three thousand million times around the 
atoms, before they could produce visible light ; and this 
swift motion has been going on in millions upon millions of 
atoms simultaneously in the tiniest flame that we can 
perceive ! 

The whole reaction has taken only the fraction of a second 
to complete itself. Short as this time is to us, yet it repre- 
sents to an atom an eternity of time within which vast multi- 
tudes of atomic events are capable of occurring, of slowly 
growing into prominence, and then gradually dying out 
again.* For example, we can calculate from the kinetic 

* Dr. Johnstone Stoney {Philosophical Magazine, 1868, p. 132, 
Vol. 36), illustrates the swiftness of the events going on within the 
atoms as follows : " The double vibrations of visible light are 
executed in periods of time which range from 1.3 to 2.6 Xio- 1 



THE WONDERS OF CHEMICAL CHANGE 61 

theory of gases that within a single second an atom of hydro- 
gen would have ample time to revolve three million million 
times about an atom of oxygen in the water molecule. 
Calling familiarly the time of revolution an " atomic year " 
we see that a single second of our time is worth three billion 
of atomic years ! So that if the above reaction between 
hydrogen and oxygen gases took only the one-thousandth 
part of a second to complete itself, nevertheless this time 
represents a vast interval of 3000 million atomic years ! 
If we, for the sake of illustration, imagined that the water 
molecules were inhabited and that the time it took an atom 
of hydrogen to revolve around an atom of oxygen in this 
molecule bore to these inhabitants the same relationship 
that the time the earth takes to travel around the sun bears 
to us, the atomic inhabitants would be quite unaware of 
the molecular catastrophe proceeding so swiftly about them ! 
The stellar heavens above us may, for all we know, be the 
theatre of a similar swift change which may complete itself 
in a few billion years. Yet so vast is this period of time 

seconds . . . these swift little motions of light are accordingly related 
to a 10- 16 second in somewhat the same way that the motions of our 
limbs are to a second of time. Now 10- 15 second is the same portion 
of a second as a second is of upwards thirty millions of years. Hence 
the motions of light bear the same relation to one second of time 
which the motion of our limbs bear to that almost inconceivable 
cosmical period — a vast succession of geological ages, during which 
several races of animals, culminating in man, have appeared, have 
lasted long, and have finally perished from our globe. ... If there 
were sentient beings with bodies which move as deftly as this ether, 
and with thoughts and perceptions as quick as their bodies are active, 
there would be sufficient time for them within a small fragment of 
one second to live the lives of all the generations of men that have 
dwelt upon this earth, thinking all their thoughts and doing all then- 
acts. The mind is almost carried beyond itself in the contemplation 
of such periods. It is from the vastness of one second in reference 
to light, that with its little waves light can travel such an immense 
distance as 298 millions of metres (186,000 miles) in that period of 
time. It puts a strain upon the mind to form a conception of the 
mere moment of time that suffices for the light of a candle, at this 
unheard of pace, to travel one hand breadth from the flame ; but 
brief as this instant is, it corresponds to what several weeks would 
be in reference to our movements. The light has had time to execute 
hundreds of thousands of its tiny vibrations/' 



62 MODERN CHEMISTRY 

that the changes now proceeding seem immeasurably slow 
to us. In the eyes of a being, however, to whom a billion 
years seem but a second, or in whom a sense of time is non- 
existent, the whole mighty universe might appear to be 
in the throes of a swift catastrophe which completes itself 
instantly ! Man, with his empires and cities, would, to such 
a being, seem but a momentary excrescence, appearing 
suddenly in the never-ending abyss of time and then 
vanishing for ever.* 

The subject of molecular collision has been discussed very 
fully by Dr. Johnstone Stoney in the Philosophical Magazine 
(1868, Vol. 36, p. 132, and 1895, Vol. 40, p. 362). Some of his 
remarks are well worth repeating : 

" . . in ordinary air about us each molecule meets with something 
like a million of encounters in something like the seventh part of 
rsWth of a second. . . the mean length of the path which a molecule 
of a gas like air passes through before meeting with another molecule 
is 7 x io-« cms. (about the three-millionth part of an inch). The 
mean duration of each of its little rectilinear excursions is about 
1.4 x io- la second {i.e. something like one and a half times the million 
millionth part of a second). This fragment of time, tiny as it is, is 
nevertheless more than 50,000 times the vastly shorter period which 
suffices for a double vibration of red light, and 100,000 times the 
duration of a double vibration of the extreme violet ray. And as 
the periods of the motions which give rise to visible light must lie 
between these limits, we are forced to conclude that, on the average, 
something like fifty to a hundred thousand of these little orbital 
motions are executed (by the atoms) between two consecutive colli- 
sions. It is now no longer surprising that the temporary perturba- 
tion caused while two molecules are whirling past each other has, 
in many cases, had abundant time to pass away early in the interval 
between the two collisions, so as to leave the greater part of the 
minuter internal motions to be executed in the undisturbed manner 

* In this connection it is interesting to note that Prof. Kapteyn 
and Mr. Edington have shown recently that two mighty streams of 
stars flowing in opposite directions through space, meet, forming 
two great intervening universes, which link into each other and pass. 
That stars often collide in space is a fact well known to astronomers, 
such collisions resulting in the formation of the nebulae and the new 
stars which flash into brightness in the heavens from time to time. 
The possibility that in the heavens there is taking place 1 reaction 
similar to a chemical reaction in wh'ch suns and worlds tsxe the part 
of atoms has gained in probability ugni the astro-physical researches 
Qi the last few years, 



THE WONDERS OF CHEMICAL CHANGE 63 

which the definiteness of the spectral lines attest to us. We also come 
to see how the motions with which the molecules dart about amongst 
one another cannot produce or intercept light ; in fact, they are far 
too sluggish — just as the motions of our fingers, or a very gentle 
waving of our hand do not produce sound. 

" An excellent way of helping to appreciate the events with 
which we have to deal in molecular physics, is to conceive a 
model of them in which the durations shall be enlarged all 600 billions 
of times. If prolonged to this extent, the most rapidly occurring 
motions in nature that are as yet known to us, viz., those periodic 
events in a gas which give rise to the lines in its spectrum, would 
swing at rates comparable with the motions of the limbs of animals, 
and would then have about as great a range from the swiftest to 
the slowest. On the same immense time scale the duration of the 
journeys of the molecules of ordinary air would average about one 
day each, while the encounter (with another molecule) may last 
twenty minutes. The motions of the limbs of animals are able to 
accomplish a good deal in a struggle lasting twenty minutes. On the 
same scale, the ten-thousandth of a second grows to be of immense 
duration, extending to 1900 years. The number of struggles (mole- 
cular collisions) to be encountered by each molecule in the ten- 
thousandth part of a second is, accordingly, the same as the number 
of days in the whole Christian Era, from the birth of Christ down 
to the end of the present century. If something can be done during 
the twenty minutes that one of the struggles may last, how great a 
task may be accomplished by such an enormous succession of them. 
It must be borne in mind, too, that these encounters are not mere 
repetitions of each other, but that each has its own definite incidents. 
Moreover, all this is what occurs in the experience of one individual 
molecule, so that we must multiply it by a thousand millions, in order 
to sum up all that may be accomplished by all the encounters of all 
the molecules within a cubic micron (a cube whose side is x^^ th 
of a millimetre. There are seventy or eighty cubic microns in 
the volume of each of the small discs in human blood) of gas in the 
ten-thousandth part of a second, and that we may in some degree 
understand how it comes to pass that opportunity is afforded in nature 
for accomplishing work which requires rare collocations of conditions 
that can but seldom emerge. 

" Such is Nature's real laboratory — events in inconceivable num- 
bers, the whole phantasmagoria of these innumerable events changing 
every instant down to its minutest details with inconceivable rapidity, 
the changes in most cases keeping within limits, but in some cases 
exploring every part of a wide range ; it is thus that those wonderful 
operations are carried on, which issue in the astonishing results that 
lie everywhere in such profusion around us. We seem almost to 
get an obscure and partial glimpse of how, in organic nature, tasks of 
the most unlikely kind are accomplished, through the needful 
opportunities now and then turning up witljin each tiny specie of_sp 



64 MODERN CHEMISTRY 



Protean a material as protoplasm, a body of which the mutations 
have probably time relations of the same order as those we have been 
endeavouring to illustrate, and whose activities are therefore more 
incessant, more various, and more complex, within every thousandth 
of a second, in every speck and corner of each living cell, than the 
mind can even conceive. It is very little man yet knows of what is 
going on abundantly about him in every stick and stone." 

With such wonderful facts facing us on every side it is 
madness to assert that the progress of Science means the 
destruction of the spirit of reverence and of wonder. To such 
criticisms Science may proudly reply in the words of the 
Earth-Spirit of Goethe's " Faust " ■ 

" At the whirring loom of Time unawed, 
I weave the living garment of the Lord." 

Indeed, owing to the advances of Science, how much more 
wonderful a world we live in than that of Milton or Shake- 
speare ? How dwarfed the mental vision of all who lived 
only a few hundred years ago appears to us now ! Where our 
predecessors saw but gleams of light and shade, we see 
billions of ethereal vibrations flashing swifter than eye or 
brain can follow. Where they saw grey walls and gentle 
breezes, we see myriads of atoms and all the wonders of 
the atomic universe streaming and flaring about us. Truly, 
every fresh advance of science makes us only more forcibly 
realise the truth of MinshulTs words : 

ft Land, Sea, and Sky ! What mystery and what wonder 
Lie hidden in the old familiar sound ! 
From surging wave and roll of mighty thunder 
To the white daisy nestling on the ground." 

* The chemical forces which drive the atoms into motion have 
for us an interest which is personal and almost tragic. For 
men and women, as well as all other living creatures, are but 
everchanging, evershifting, swarms of atoms which are driven 
along their endless dance of change by these same chemical 
forces. Every human deed, every mechanical action 
of wind, fire or water, is directly or indirectly caused 
by them. The light-hearted laughter of a young girl, the 
quick glance of her eyes, the lithe movements of her limbs 
are, just as much as the tottering movements of an old 
man or the cry of a child or the gallop of a horse, purely 



ns 






THE WONDERS OF CHEMICAL CHANGE 65 

mechanical effects due to the swift rush of millions of tiny 
atoms suddenly and irresistibly urged together or apart by 
mighty chemical forces released in a moment by the action of 
the will ! These chemical forces build up, atom by atom, 
a thing of life and beauty, such as a flower, a bird, a woman, 
from a heap of dust, water, and gas, and then as the years 
roll on they undo their work again, and cause young leaves 
to grow old and wither and bright eyes to grow dim and 
strong bodies to grow stiff and feeble and die. Then, 
wonder of wonders, they convert that which was, perhaps, 
a brilliantly hued bird flitting in a tropical grove, or a merry 
sweet-faced maiden singing blithely in the sun, into the gases, 
water, and dust which surrounds us now ! 

Who can say what millions of lives the rain-drops splashing 
in our face, or the dust clouds rolling down the road, have 
entered into at some time or other of their career ? What 
tales of hope and fear, of joy and sorrow, of times and races 
vanished thousands of years ago, they could unfold if we 
could make them relate their history to us ! Chemical forces, 
therefore, reign supreme, not only on this world, but also 
throughout the stupendous universe of worlds and suns, 
which indeed are merely vast collections of atoms. For all 
actions, all events occurring in space and time are but the 
results of the forces exerted by one swarm of atoms on 
other swarms. 

In Elgar's wonderful version of the old Norse legend of 
King Olaf, the great war-god Thor is made to declare that : 
" Force rules the world still, 

Has ruled it, shall rule it ; 

Meekness is weakness, 

Strength is triumphant, 

Over the whole Earth 

Still it is Thor's .Day ! " 

If Thor's words are made to apply to chemical forc« I do 
not think that Science will dispute the correctness of his 
dictum. Sir Lewis Morris has in our own time beautifully 
expressed the same idea in the words : 

" There is no God but Force, 
Which, working always on its destined course, 
Speeds on its way and knows no thought of change." 



66 MODERN CHEMISTRY 

To master the symbolical language of chemistry, so as to 
understand fully what it expresses, is a great step towards 
mastering the science itself. We will therefore now explain 
the use of symbols for expressing chemical changes. To 
each element we give a symbol, usually the first letter of the 
Latin name, which is often also that of the English name. 
Thus O stands for oxygen, H for hydrogen, S for sulphur, 
Cu for copper (cuprum), Ag for silver (Argentum). These 
letters signify more than that a particular substance takes 
part in the reaction. They indicate that element is present 
in the quantity by weight which is expressed by its atomic 
weight. Thus O does not stand for any quantity of oxygen, 
but for one atomic weight, i.e., 16 parts by weight. (See 
table of atomic weights in chapter III.) H always stands 
for one atomic weight, i.e., I part by weight of hydrogen ; 
and in like manner S, Cu, and Ag stand invariably for the 
atomic weights 32, 63, and 108 respectively, of these 
elements. 

By placing the symbols of elements side by side a com- 
bination of elements is signified, thus : 

HCl (hydrochloric acid) represents a molecule consisting 
of one atom of hydrogen weighing one, united with one atom 
of chlorine weighing 35.5, the combined weights standing 
for 1+35.5 =36-5 parts of hydrochloric acid. 

CuO (copper oxide) represents a molecule consisting of 
one atom of copper weighing 63 united witii one atom of 
oxygen weighing 16, the whole weighing 63 +16 =79. CuO, 
therefore, stands for 79 parts of copper oxide. Atoms of the 
same element may unite together : thus, H-H and 0-0 (or 
as they are more usually written, H 2 and 2 ) stand, respec- 
tively, for one molecule of hydrogen and oxygen gas, each 
molecule consisting of two atoms united together, the 
molecule of hydrogen weighing 2 and that of oxygen 2x16 
or 32. If the molecule contains more than one atom of any 
element, this is indicated by placing a small number below 
the symbol of the element. Thus H 2 signifies that this 
molecule contains two atoms of hydrogen or two parts, 
united with one atom of oxygen or 16 parts, the whole making 
up 2+16 =18 parts by weight of water. 



THE WONDERS OF CHEMICAL CHANGE 67 

Again CaC0 3 (calcium carbonate or chalk) represents a 
molecule consisting of one atom of calcium, weighing 40, 
united with one atom of carbon weighing 12, and three atoms 
of oxygen each weighing 16. So that CaC0 3 represents 
40 +12 +16 +16 +16 =100 parts of chalk. 

Let us now illustrate the utility of these chemical symbols 
for expressing chemical changes. If we throw a pinch of 
chalk dust into hydrochloric acid, we see a momentary 
effervescence, which passes and leaves the acid apparently 
much as it was. No striking outward phenomena have 
occurred to awaken our surprise or challenge our attention. 
Yet in this instant of time a wonderful change has taken 
place. Nothing less, indeed, than the destruction, swift 
and terrible, of a whole atomic universe. The chalk as it 
falls into the acid represents the intrusion of one vast stream 
of whirling atomic systems into another equally vast stream. 
In an instant millions upon millions of chalk molecules are 
colliding with equally vast numbers of hydrochloric acid 
molecules. Each time a molecule of chalk encounters 
a molecule of hydrochloric acid, both tiny atomic systems 
are irretrievably shattered and their fragments rearrange 
themselves into other atomic systems. The slight efferves- 
cence noticed marks the swift rush of one series of these 
rearranged atoms, in the form of a colourless gas called 
carbon dioxide, whose molecules consist of two atoms of 
oxygen whirling round one atom of carbon. ^ Water mole- 
cules and calcium chloride molecules are similarly born, and 
go whirling off among the mass of molecules which constitute 
the hydrochloric acid. Thus an event, one of innumerable 
other similar events taking place ceaselessly around us, 
apparently so insignificant as to scarce merit our attention, 
really represents a stupendous catastrophe in the atomic 
universe. At first sight it would seem incredible that all the 
bewildering complexity and intricate detail which neces- 
sarily attends the collision of billions of atomic systems, 
each collision being accompanied by its own train of events 
which distinguishes it from all the others, could ever be 
simply and concisely expressed by chemists. Yet chemists, 
by means of their symbolical language, not only do this, but 



68 MODERN CHEMISTRY 

they actually express the final result quantitatively ! In 
order to do this the chemical formulae of the materials taking 
part in the reaction are placed side by side on one side 
of an equation, and the products formed as the result 
of their collision are placed on the other side. Thus in 
expressing the action of hydrochloric acid upon chalk all 
that a chemist would say is that the hydrochloric acid 
decomposes the chalk, giving rise to the colourless gas, 
carbon dioxide, and the white solid calcium chloride, and the 
liquid water. And he would represent it by the following 
equation :* 

CaC0 3 + 2HCI = CaCl 2 + H a O + CO a 

Hydrochloric Calcium Carbon 

Chalk Acid Chloride Water Dioxide 

40 + 12 -f 3 + 16 2 (1 + 35-5) 40 + 2 x 35-5 2 + 16 12 + 2 x 16 

100 parts 73 parts in parts 18 parts 44 parts 

The sign = is used since the weight of the products on the 
left hand side is equal to the weight of the products on the 
right hand side, a necessary consequence of the indestruc- 
tibility of matter (Chapter L). The sign+ connects the pro- 
ducts and signifies " together with." The equation is an 
expression of the fact that ioo parts of chalk (Ca =40, C = 12, 
3 =3 xi6 =48 and 40 +12 +48 =100) unite with 73 parts 
of hydrochloric acid (H =1, CI =35.5, and HC1 =1+35.5 
=36.5 and 2HCI = 73) to produce in parts of calcium 
chloride (Ca = 40, Cl 2 =2 X35.5 =71, and hence CaCl 2 =40 
+71 =111) and 44 parts of carbon dioxide (C = 12, 2 =2 x 16 
= 32, hence 12 +32 =44) and 18 parts of water (H 2 =2, 
O = 16, H 2 = 2+16 = 18). 

Hence it is clear that the quantity of any one of the pro- 
ducts obtained from a given weight of chalk can be easily 
ascertained by a simple calculation, and that the above 
equation is a quantitative expression of this change. Every 
chemical equation used throughout this book is, therefore, 

* An account of the ionic theory of chemical change would in 
these earlier chapters merely confuse the beginner. We will therefore 
content ourselves by here remarking that in solution it is probable 
that the molecules break up into electrically charged parts called 
" ions " and that it is these " ions " which chemically interact, not 
the undecomposed molecules. 






THE WONDERS OF CHEMICAL CHANGE 69 

a very wonderful thing. It represents the quantitative 
results of a number of atomic collisions repeated millions of 
times over. It is the telegraphic announcement in chemical 
language that a series of atomic universes have been 
destroyed by collision and that others have been built up 
out of their ruins. 

The reader is now ripe for a glimpse of one of the most 
marvellous achievements of modern science in the region of 
the invisible underworld of atoms. Indeed, so incredible 
are some of her successes in this direction that the reader 
may at first be tempted to think that 

" Blinded by some keen too-vivid gleam 
Of the unseen^" 

science has strayed from the paths of fact into those of 
V fancy. 

We know that a molecule is a small collection of atoms so 
diminutive in bulk that the whole structure is less than the 
a-wloooo of an inch in diameter and consequently far 
below the limits of anything that we can see in the very best 
microscope. Yet Science claims that she has not only 
succeeded in ascertaining that each molecule has a definite 
structure, but that she knows many of the details of that 
structure. She knows not only the number of atoms in the 
molecule, but also how they are arranged or grouped together ! 
Indeed almost all the great chemists of the world are at 
the present time engaged in investigating this very problem, 
and what is more, they have, in many cases, succeeded in 
solving it. We have reached as much certainty in regard 
to the grouping of the atoms in the molecules of a very large 
number of substances, as we have in regard to any phenomena 
beyond the direct reach of our senses. This is a feat of the 
same order as placing an ordinary watch 75,000 miles away, 
say between nine and ten times the distance of New Zealand 
from London, and then ascertaining at this distance the num- 
ber of wheels it contains, and how these wheels are arranged 
within it ! If a friend held up a watch at a distance 
nearly a mile from us, how few of us could see it, much less 
say how it was constructed ! How then have these wonders 



7o MODERN CHEMISTRY 

been achieved ? In the simplest way in the world. By 
merely studying all the changes which a substance will 
undergo. 

Let us illustrate this by the case of sulphuric acid, a sub- 
stance whose chemical formula is H 2 S0 4 . In other words 
it contains two atoms of hydrogen united to one atom of 
sulphur and four atoms of oxygen. If we drop a metal 
into a dilute solution of this acid we get off all its 
hydrogen, thus : 



H 2 S0 4 


Zn = 


= ZnS0 4 


+ H 


Sulphuric 


Zinc 


Zinc 


Hydrogen 


Acid 




Sulphate 





Hence we can remove all the hydrogen from the mole- 
cule without removing its oxygen ; but we cannot remove 
the oxygen without simultaneously removing the hydrogen 
atoms as well. This shows that the hydrogen atoms are 
directly joined up to the oxygen atoms. The removal of 
the two oxygen atoms and with them the two hydrogen 
atoms may be achieved by adding phosphorus pentachloride, 
PCI 5 , to the sulphuric acid, thus : 

§§>S0 2 + PC1 5 = £!> s °2 + POCI3 + H 2 

Sulphuric Phosphorus Sulphonyl Phosphorus Water 

Acid Pentachloride Dichloride Oxychloride 

Hence we must write the sulphuric acid molecule as fol- 
lows : 

The lines connecting the atoms show how the atoms are 
linked together. This constitution clearly explains why we 
can remove hydrogen atoms without removing oxygen, and 
why we cannot remove two of the oxygen atoms without 
simultaneously removing the hydrogen. The two remaining 
oxygen atoms are very intimately bound up with the sulphur 
atom and cannot be easily removed. The molecule thus 
pictured is a system in motion. It is in its way a sort of 
tiny planetary system with the atoms whirling round with 
very great speeds. Yet the crude formula of the chemist 
depicts it as a system in a state of supreme repose. Let us 



THE WONDERS OF CHEMICAL CHANGE 71 

try, therefore, if we cannot read into the stiff lines of the 
constitutional formula some kinetic interpretation. 

Let us first consider the case of a system like the earth and 
moon. Here the moon revolves round the earth and accom- 
panies it on its journey through space. The moon is thus 
in chemical language " linked up " to the earth, and a 
chemist would express this relationship by a " constitu- 
tional formula" like this : 

M— E 

where E stands for the earth and M for the moon. 

Now is this not exactly analogous to the constitutional 

formula of a simple molecule ^ _ 

like that of hydrochoric acid / (\JMQON 

or copper oxide which are / 

expressed by the following J f^\ " ' * ~" ^ s 

constitutional formulae ? \ '^-^ / \ 



H— CI, and Cu— O. \( *r-*-'" / \ 

The band or " link " join- / *"" /^TS } 

ing the two atoms has here / w^y ; 

the meaning that the one > ^— r / 

atom accompanies the other \ / 

on its journey through space, \ / 

each atom probably revolving \ ^** 

one about the other in the ***-.. __--^ 

same way that the moon re- Fig. 8.— The Solar System, showing 

volves about the earth. Now now tne moon g° es witn tne eartn 

t , . i 1 j and the earth with the sun. 

let us take a somewhat more 

complicated system, such as that of the moon, earth, and sun. 
Here the earth revolves round the sun and the moon around 
the earth in the way depicted in Fig. 8. The earth is, so to 
speak, connected or linked to the sun, and the moon to the 
earth Hence we could pluck away the moon from the whole 
system without removing the earth ; but if we plucked 
away the earth, the moon would be removed with it. Is not 
this u exactly the same phenomenon that we have met with in 
the case of the sulphuric acid molecule, where we found 
that the hydrogen atoms could be removed without removing 



72 MODERN CHEMISTRY 

oxygen atoms, but that oxygen atoms could not be removed 
without removing hydrogen atoms with them ? A chemist 
would express these relations which exist between the sun, 
earth, and moon, by a constitutional formula such as this : 

M— E— S 

where M, E, and S stand for the moon, earth, and sun. 

As in the case of the sulphuric acid constitutional formula, 
the dashes merely show how the particles are linked together ; 
and it is possible that the physical interpretation is the same 
in both cases. 

Just as we removed in succession the moon and the earth 
from the sun in order to determine the constitution of the 
system, so chemists remove in succession the different 
atoms of the molecule in order to elucidate their constitution. 
The agents which they employ for picking off the atoms are 
collisions with different sorts of molecules. In other words 
the chemist " treats " the molecules of the substance with 
other sorts of molecules and then studies the decomposition 
products. In this way a marvellous insight is obtained 
into the actual structure of the molecules. 

" In all compounds," says Ira Remsen* " the attempt is 
made by means of a thorough study of their chemical 
conduct, to trace out the connections existing betw r een the 
constituent atoms. When this can be done for all the atoms 
contained in a molecule, the structure or constitution of the 
molecule or of the compound is said to be determined. . . . 
The formulas are but the condensed expressions of the 
conclusions which are drawn from the reactions/' Now 
reverting to our planetary model we get the following inter- 
pretation of our constitutional formula of the sulphuric 
acid molecule : Firstly, a central sulphur atom (marked i 
in Fig. 9) around which all the other atoms rotate. Next 
come two oxygen atoms (marked 2 and 3) revolving one 
about the other, and the combined pair circulating about 

the central sulphur atom, thus expressing the relation S< 1 

Outside of these come two oxygen atoms (4 and 5) to each 
* Introduction to " Organic Chemistry," p. 16. 



THE WONDERS OF CHEMICAL CHANGE y> 
of which a satellite in the shape of a hydrogen atom is 

XT r\ 

provided. We thus express the relation „ o^* ^ e nave 

thus obtained a kinetical interpretation of the entire con- 
stitutional formula jt q > S < i of sulphuric acid. Probably 



VHS2SSMH 









m 



wsszasa 



mnsstsm 






HEEEStSMBk 



J? J/ / 



Fig. q. — Imaginary Representation of a Sulphuric Acid Molecule. This 
probably consists of a tiny atomic planetary system consisting of a 
central sulphur atom around which are swiftly revolving a number of 
other atoms. 

the molecule itself is rotating rapidly and the whole may 
appear like a rapidly rotating wheel.* Other constitutional 
formula can be similarly interpreted. 

* We have indisputable evidence that vastly swift whirling 
motions actually do go on within the molecules of many substances, 
the motion being in some substances from right to left and in others 






74 MODERN CHEMISTRY 

However interesting and instructive such models may be 
in helping the beginner to realise what the constitutional 
formulae of the chemist really mean, the reader must be 
cautioned against accepting them as absolutely true repre- 
sentations of the molecules. For example, there are some 
facts which seem to indicate that the sulphur atom has a 
distinct shape in space and that the atoms rotate round 
fixed points on its surface rather than round it as a whole, 
like planets, round the sun. 

For the present, however, our models may be taken as 
representing the facts closely enough. In many cases they 
probably correspond to a real physical representation of 
the molecules. 

Let us now picture to ourselves with the aid of these 
models the course of the chemical reaction between phos- 

from left to right. For example, in magnets we know that the 
majority of the molecules are arranged so that the orbits of the 
majority of the electrons, which revolve around the atoms like the 
planets round the sun, all lie in parallel planes, like the planets in 
the solar system, with the revolutions in the same sense ; and in 
permanent magnets this parallelism is maintained by the mutual 
attraction of the orbits of the different molecules. Again, when we 
send a ray of plane polarised light through a certain modification 
of tartaric acid (a substance composed of hydrogen, oxygen, and 
carbon, much used for making effervescing powders) we find that there 
is a swift rotation going on within the molecules all in the same 
direction which rotates the plane of polarisation of the ray to the 
right. If now we send the ray through another modification of 
tartaric acid, we find that the ray has its plane of polarisation rotated 
to the same extent, but now to THE LEFT ! Chemically the two 
modifications are similar. The only difference seems to be the 
physical one that the swift whirl going on within the molecules is in 
opposite directions in the two modifications. Many other similar 
cases are known. The investigation of these " optically active " 
bodies, as chemists call them, has in the hands of Pasteur, van't Hoff, 
Le Bel, Wislicenus, Pope, Kipping, and others, taught us that 
certain atoms, like carbon and silicon, have a definite shape, that of 
a tetrahedron, and that the attached atoms rotate round fixed 
points at the corners of the tetrahedron. For further information 
on this wonderfully interesting science of " Stereo-Chemistry," 
which deals with the shape of the atoms, we may refer the reader to 
van't Hoff's " The Arrangement of the Atoms in Space " or to 
Stewart's " Stereo-Chemistry." We have briefly touched on the 
subject in Chapter II. 



THE WONDERS OF CHEMICAL CHANGE 75 




1 
■3 

aJ 
O 

u 

S 4 

& 



7 6 



MODERN CHEMISTRY 



phorus pentachloride and sulphuric acid, a reaction which* 
we have already discussed (p. 70) . The change is represented 
by the following equation : 



(HO) 2 S0 2 

Sulphuric 
Acid 



+ pci 5 . 

Phosphorus 
Pen tachloride 



POCI3 

Phosphorus 
Oxvchloride 



S0 2 CI 2 

Sulphonyl 
Dicnloride 



H 2 

Water 




Fig. 



-Reaction between PC1 5 and H a S0 4 , 
coAiide, 



We must imagine the molecules of PC1 5 and H 2 S0 4 
rushing together in opposite directions, with all their atoms 
whirling round them, as in Fig. 10. They meet (Fig. 11). 
The individual atoms become entangled each in the other's 



THE WONDERS OF CHEMICAL CHANGE 



77 



sphere of influence. Two chlorine atoms rush in towards 
the sulphur atom and continue revolving about it. All is 
over in an instant, and there fly away (Fig. 12) the three 
molecular systems POCl 3 , H 2 0, and C1 2 S0 2 , produced 
by the shattering of the original molecular systems. 

How serious a matter such a collision as that here pictured 
must be for the constituent atoms of the molecules, will best 




Fig. 12. — Reaction between PC1 5 and H 2 S0 4 . III. Formation oz 
the molecules POCl S) H 2 0, and S0 2 C1 2 as the result of collision. ,„ 

be realised by imagining the encounter of our solar system 
with one of the dark suns of space, an event which, perhaps, 
would afford the nearest analogy that we are acquainted 
with to such a molecular collision. If the sun and star 
actually collided both bodies would be reduced to a mass 
of flaming gas within an hour, and the sudden generation of 
heat would be so great that the whole surface of the earth 



78 MODERN CHEMISTRY 

would be burnt to a cinder within a few seconds. Perhaps, 
indeed, the earth would be actually gasified and, along with 
the other planets of the solar system, overwhelmed 

" In unremorseful folds of rolling fire." 

More probably, however, such a dark sun would sweep 
through the solar system without actually colliding with any 
planet, and after grazing the sun like a comet, would retreat 
along a curve like an ellipse, bearing with it into space some of 
the planets of the solar system, and leaving behind it some of 
its own. Even in this case the event would be an unpleasant 
one. For if the invading sun approached the earth, its attrac- 
tion would uplift great areas of the earth's crust, tearing 
them away and releasing strains and forces underneath. 
Such terrible volcanic eruptions, such floods of lava, such 
storms and earthquakes would result, that probably every 
living thing upon the earth would be killed in the course of 
a few hours, except perhaps a few of the lowest bacteria. 
If it approached the sun, the same pulling action of gravity 
would cause great arms of flame, millions of miles long, to 
leap out from the sun. And finally, if such a body merely 
approached our system, it might produce such an alteration 
in the orbits of the planets as to make them unstable, and 
give rise to the possibility that the planets themselves would 
fall into the sun. 

The facts that we have discussed in this chapter led the 
great Russian chemist, Mendeleef, to draw some interesting 
comparisons between the atomic and stellar universes. 
He compares molecules of hydrogen, oxygen, and water to 
the systems of double or triple stars found in space. In a 
work published shortly before his death he compares in 
beautiful language the atoms to the heavenly bodies, such 
as the sun, planets, satellites and comets, which are eter- 
nally wheeling in space, and he then likens the building up 
of molecules from atoms, and of substances from molecules, 
to the building up of systems, such as the solar system, or 
of those wonderful twin stars — colossal suns circulating about 
each other in highly elliptical orbits — which modern astro- 
nomy has revealed to us, and even of whole constellations, 



THE WONDERS OF CHEMICAL CHANGE ,g 

which likewise are built up of individual bodies. So that 
according to Mendeleef the whole visible stellar universe, 
with its millions of rushing suns, is merely on the large 
scale an image of what the atomic universe is on the small 
scale. He believes this to be no mere fancy, but " a reality 
which directs the course of all chemical research, analysis 
and synthesis/'* 

The modern electronic theory of matter, as developed 
recently in the hands of the Cambridge School of physicists, 
with J. J. Thomson at their head, would make the resem- 
blance between the solar system and an atom even more start- 
ling, as has been shown by Fournier d'Albe in his book on 
" The Electron Theory," where the analogy is worked out 
in detail. He shows that if the solar system is but an atom 
on the large scale, the sun must be regarded as a positive 
nucleus and the planets as electrons. He then shows that 
the sun actually is charged positively and the planets 
negatively, although the electrical forces which act between 
them is not sufficient to effect or control their motion to a 
perceptible extent, so that here the analogy breaks down. 
He points out that the mass of Jupiter is the one-thousandth 
part of that of the sun, and consequently approaches the mass 
of an electron in comparison with that of a hydrogen atom. 
The mass of the earth is only the three-hundred thousandth 
part of that of the sun and so bears the same ratio to this body 
as an electron bears to a heavy atom, like that of mercury 
or lead. Like the atoms of matter, the solar system as a 
whole is electrically neutral, the negative charges on the 
planets counterbalancing the positive electrical charge on 
the sun. He shows, moreover, that if a neutral external 
solar system were to approach our solar system and were 
to capture a planet like Neptune or Uranus, we should have 
an illustration of what is so common an event in chemistry 
of two atoms combining, and then separating with opposite 
electrical charges — our solar system being positively charged, 
because it has lost a negative electron (Neptune), while the 

* " A Chemical Conception of the Ether," p. 6 (1904). The same 
idea occurs in one or two places in his wonderful book, "The 
Principles of Chemistry." 



8o MODERN CHEMISTRY 

other solar system would be negative because it has gained 
a negative electron. 

Extending these observations to the whole visible universe 
he points out that the individual stars are separated so 
widely that they do not interfere with each other's motions 
or planets to an appreciable extent, and that it therefore 
approaches in constitution to a gas rather than to a liquid 
or solid. In fact, if the Milky Way, with its millions of suns, 
were reduced in magnitude in the proportion that an 
electron bears to an atom, it would appear of about the same 
size and complexity as a human blood corpuscle with its 
swarming millions of atoms. In order to achieve such a 
reduction of the visible universe we must diminish its 
magnitude in the ratio of io 22 to i, and if we do this we find 
that the solar system, with a radius of io 14 cms, becomes 
then of atomic dimensions, with a radius of io- 8 cms.* The 
distance between our sun and the nearest fixed star is about 
io 18 cms. and this when reduced in the same ratio becomes 
io- 4 cms.,* which is approximately the mean free path of a 
molecule in a somewhat attenuated gas. 

On the other hand if we magnify the tiny world of the 
atom by the factor io 22 leaving all the velocities unchanged, 
we should then cause an oxygen atom, or any similar atom, 
to become of the same size as the solar system, and its two 
negative electrons would closely resemble Neptune and 
Uranus both as regards size, distance from the centre, and 
period of revolution. 

The interior planets, such as the earth, would then repre- 
sent magnified electrons, which in the atoms cause the 
phenomenon of magnetism and radiation. Indeed, as 
Fournier d'Albe points out, the tiny electrons may have a 
constitution resembling in every particular that of the earth, 
and yet we should not only never become aware of this on 
account of the almost inconceivable minuteness of these 
bodies, but such a structure would not affect their astrono- 
mical or electrical properties in the slightest. The electron 
may be a veritable microcosm, " a world on which fife 
may flourish not very different from fife upon this earth," 

* io- 8 means, T ^, i.e., 10 ooSoooo I similarly io-« means jfe, or j^^. 



THE WONDERS OF CHEMICAL CHANGE 81 

without any one being the wiser. Such thoughts make us 
realise that the universe may have within it depths of 
complexities^altogether unsuspected by ourselves. Indeed 
the authority referred to points out that if our world and all 
that is therein were suddenly reduced by some magical 
power to atomic dimensions, our instruments would never 
indicate, and we should never know, that such a change had 
taken place, because space and time were simultaneously 
diminished in the same proportion. Conversely if an intelli- 
gent inhabitant of our electronic microcosm were suddenly 
transferred to our world, and managed to retain his mental 
characteristics unchanged, our life here, busy as it seems to 
us, would represent to him a changeless eternity, since in a 
single second of our time the electronic world has time to 
revolve billions of times round its central sun. His atomic 
years are almost infinitely shorter than ours and his sense 
of time almost infinitely finer. Time and space are, after 
all, merely relative conceptions.* . 

Such thoughts of a minute microcosm insensibly remind 
us of Morris's words : — 

" Where did the idea dwell 
Which held within the atom and the cell 
The whole vast hidden Universe, sheltered well, 
Till the hour came to unfold it, and the need ? " 

The reader, however, must be warned not to press such 
analogies too closely. Such wide differences exist between 
gravitational and chemical forces that it is doubtful whether 
a direct comparison can be made without the grave risk of 
misleading the student. So far as we know, the chemical 
phenomena of valency, stereo-chemistry, and crystallography 
are not paralleled by the stars. The atomic and the 
Newtonian universes may be and probably are built up on 
entirely different models. 

* For a further account of these interesting ideas of Fournier 
d'Albe the reader is referred to his works. 



CHAPTER V 

WATER 

The antiquity of the ocean is immense. Byron's words : 

" Time writes no wrinkle on thy azure brow. 
Such as creation's dawn beheld, thou rollest now ! " 

are probably more scientifically exact than even the poet 
imagined ; for as far back into the vista of bygone ages as 
the science of Geology goes, we always find that the great 
ocean was composed of water as it is now, water swept by 
storms and tides, water swarming with a myriad forms of 
life. It is the land not the ocean that has changed. The 
waves of the early oceans broke against shores which have 
long since vanished ; while fertile islands and great conti- 
nents which then existed, supporting innumerable forms of 
life, are now buried deep under the sea, a fact which was 
expressed by Tennyson in the well-known lines : 

" There rolls the deep where grew the tree, 
O Earth, what changes hast thou seen ! 
There where the long street roars hath been 
The stillness of the central sea." 

"^ During the ages which have elapsed since the first oceans 
were deposited the whole order of creation has had time to 
evolve, animalacule ascending to man, diatom to mighty 
trees. Nevertheless, throughout all this vast time the sea 
has remained unchanged, " the same yesterday, to-day and 
forever." The very spray which dashes in our faces as we 
walk along the sea-coast has bathed animals and plants which 
lived millions of years ago, and probably it will bathe plants 
and animals living millions of years hence ! Compared with 
the ocean man is a thing of yesterday. All this has been 

82 



\ 



WATER 83 

expressed in grand and beautiful language by the American 
poet Braithwaite in his Ode to the Sea.* 

" The earth is our mother, but thou — thou art father of us and ol 
time ; 
For all things now were not when thou wast strong in thy prime. 
There was silence first, and then darkness, and under the garment 

of these 
Was the body of thee in thy might, with its infinite mysteries. 
****** 

For earth he made out of dust, for change and defeat in the blast ; 
But thee he made eternal, thro' aeons and aeons to last, 
Unmarked by sun or wind, and supreme where thy waves are 

tossed ; 
Not an inch of thy beauty to perish, not an ounce of thy might 

to be lost." 



It is possible to arrive at an estimate of the age of the 
ocean. Prof. Joly has shown that if we calculate the amount 
of salt yearly added to the sea by means of rivers, and com- 
pare this with the amount of salt already in it, one must 
conclude that at least 100 million years have elapsed since 
the first waters of the ocean were deposited ! 
•^ The amount of water upon the globe is truly stupendous. 
The waters of the ocean alone would, if gathered together 
in one mass, form a globe about 850 miles in diameter ! f 
Over three-quarters of the surface of the globe is covered with 
water. The average depth of the depression occupied by 
the ocean is 14,640 feet, or nearly three miles. The greatest 
known depth of sea is 31,700 feet, or 6 miles. In these 
depths an utter silence and darkness has reigned for ages ; 
no human eye has ever beheld these abysmal valleys, no ripple 
has ever broken upon their shores, no play of light from 
above has ever illuminated their mighty slopes. Their 
waters are cold as melting ice itself. The pressure of the 
water in these silent and dark valleys is enormous, being 
about six tons to the square inch. The stoutest steam boiler 
ever made by man would yield and tear like tissue paper 
under such a pressure ; and yet, in spite of this, a world of 

* Century Magazine (1907), Vol. 74, p. 710, reproduced by kind 
permission of Macmillan & Co. 

+ Bonney, " The Story of our Planet," p. 14. 



S 4 MODERN CHEMISTRY 

animals, many of them quite unknown to man, live in these 
dreadful deeps. Kipling in his " Sea Cables " has drawn 
a vivid picture of the bed of the deep ocean : 
" The wrecks dissolve above us ; their dust drops down from afar 
Down to the dark, to the utter dark, where the blind white sea- 
snakes are. 
There is no sound, no echo of sound, in the deserts of the deep, 
Of the great grey level plains of ooze, where the shell-burred cables 
sleep."* 

For the origin of the mighty masses of water which con- 
stitute our oceans we must go back to a period in the history 
of our globe long antecedent to geological history, when our 
world still formed part of the vast gaseous nebula from 
which the solar system evolved. This nebula contained the 
elementary gases hydrogen and oxygen. As it cooled these 
gases gradually combined to form (as we will presently 
show) water vapour. Presently when the world condensed 
to a white hot fluid mass, it was encircled with a vast girdle 
of invisible water vapour topped with enormous clouds of 
steam. The whole of the huge volume of water which now 
stretches from continent to continent and girdles the globe 
was then supported in the state of high pressure steam by 
the molten surface of the earth. The pressure exerted by 
this and other gases which have long since disappeared into 
the earth's crust, must have been enormous. It may have 
been as much as ten tons on the square inch ! The tempera- 
tures and pressures within the boilers of our most powerful 
steam engines are quite insignificant when compared to those 
which prevailed within such a giant boiler as our earth's 
surface formed at that remote time. These conditions 
did not last very long. The temperature of the world's 
surface rapidly fell from a white heat to a low red heat. 
When it reached a temperature of about 370 C. water for 
the first time began to be deposited upon the surface of the 
globe, this being the highest temperature at which steam 
can condense to water at a high pressure. 

This was a marvellous period in the history of our planet ; 
for almost the whole of the vast mass of liquid now found 

* From " The Seven Seas," by kind permission of Mr. Kipling 
and his publishers, Methuen & Co. 



WATER 85 

in the oceans condensed from steam to water within a 
period which Lord Kelvin reckons could not have exceeded 
one hundred years, and which Arrhenius thinks could not 
have been longer than a few thousand years ! First there 
came on a Niagara-like torrent of almost red-hot rain (at a 
temperature of 370 C). The volume of the water then des- 
cending from the sky can now scarcely be realised ; perhaps 
a feeble representation of these early torrents may be seen 
in the water-spouts which sometimes devastate tropical seas ; 
for huge quantities of water must have been ever condensing 
in the upper cool regions of the air and continually pouring 
upon the red-hot surface of the earth below, only to be hurled 
aloft again, mingled with molten debris, in a series of vast 
explosions. How strange that early world must have looked. 
Imagine its surface a vast plain of liquid fire ; above, black 
driving vapour and great clouds of steam glaring red from 
the glow of the bubbling molten rocks beneath. Below, 
hurricanes and cyclones inconceivably more terrible than 
any that now occur upon the earth, continually sweeping 
vast masses of rolling vapours and liquids in huge waves 
across the blazing seas ! 

This went on during the whole time (and probably for 
some time previously too) that elapsed between the forma- 
tion of the first solid crust of the earth (at about iooo°C.) 
and the cooling of this crust, a few thousand years later, to 
ioo° C. If astronomers are to be believed such scenes are. 
even now being enacted on the mighty planets Jupiter, 
Saturn, Neptune, and Uranus, although it is hard to realise 
this when we see them shining with such apparent quiet 
in the sky at night. 

The temperature of the oceans then rapidly sank from 
ioo° C. until it reached 55 C, a temperature at which certain 
seaweeds (Algae) now exist in the hot springs of New Zealand 
and America. Since then the temperature of the ocean has 
declined gradually until it has reached its present value. 
According to Arrhenius the earth must have been in a fit 
condition for maintaining life quite a short time after the 
deposition of the oceans.* 

* Arrhenius, " Das Werden der Welten," p. 36. 



86 MODERN CHEMISTRY 

The reader, however, must not imagine that the earth 
has even now completely cooled. Its interior is still white 
hot, perhaps so hot as to be gaseous. Its surface is still at 
a temperature nearly 300 C. above that of external space. 
Indeed to beings accustomed to the coldness and darkness 
of external space (for away from the immediate vicinity of 
our sun all is as dark as the darkest night and almost as 
cold as the absolute zero of temperature itself) the world 
would be almost as hot as molten lead is to us ! It must 
not be forgotten that the earth's surface is still so hot that 
over three-quarters of it is in a fused or molten condition ! 
For water is nothing but a molten rock. Ice, in fact, has 
as much right to be regarded as a rock as has quartz or 
granite. Indeed, in early times vast seas of molten granite 
and quartz existed just as there now exist seas of molten or 
fused ice. 

The process of cooling has by no means come to an end. 
The earth is still cooling and there will surely come a time 
when its average temperature will sink from its present 
value (17 C.) to nearly — 273 C. — the absolute zero of 
temperature itself.* 

Even at the present time the temperature of the world 
is only slightly above the temperature at which all its water 
will pass into the solid state. Indeed the process of solidifica- 
tion has already commenced. Large regions exist where all 
the water has passed permanently into the solid condition ; 
and these regions will extend with time until all the seas and 
the mighty oceans themselves will freeze and be converted 
from top to bottom into vast masses of ice. Water will 
appear to the inhabitants of future days (if any exist) as 

* The present temperature of the earth's surface depends essen- 
tially upon the radiation from the sun. The amount of heat filtering 
up through the badly-conducting crust of the earth is not sufficient 
to warm the surface much. The cooling will follow on account of 
the diminution of heat and light from the sun. For there exists 
little doubt that the sun will in the course of time grow dim and finally 
go out, leaving the world dark and desolate. Future research, 
however, must decide to what extent these conclusions must be 
modified owing to the presence of heat-evolving radium disseminated 
throughout the earth and sun. 



WATER 



87 



solid deposits of mineral matter presenting to them much 
the same appearance as the white masses of marble rocks 
in certain parts of the world present to us ! 

Water is not confined to our earth alone. It is said to 
have been detected on our sister planet Venus, a body about 
the same size as the earth. She is surrounded by a deep 
dense atmosphere in which float vast masses of white clouds. 
These, no doubt, are similarly constituted to the clouds 
which occur on the earth and consist of minute drops of 
water. Some observations by Cruithuisen and Trouvelet 
seem to indicate the presence of snowy polar regions. Very 
probably under the layer of clouds which cover this planet 




Fig. 13. — Section of the Earth's Crust. 

there exist large oceans and rivers similar to our own. Water 
certainly exists on Mars. It has been detected there by means 
of the spectroscope. We can actually see the snow collecting 
around her poles in the winter time which in the spring rapidly 
melts and turns into dark masses of water. Sometimes, 
indeed, during the summer months, the masses of snow 
melt away completely, a thing which never happens in our 
polar regions. The surfaces of the larger planets, Jupiter, 
Saturn, and Neptune are largely composed of vast steam 
clouds floating above a hot mass of molten rock. Water is 
thus generally disseminated throughout the solar system. 
It is, in fact, a universal body. Let us now leave the solar 
system altogether and cast our eyes upon : 

" The fires which arch this dusky dot — 
Yon myriad worlded way — 
The vast sun-clusters' gathered blaze, 
World-isles in lonely skies." 



88 MODERN CHEMISTRY 

We see that there exist scattered throughout the limitless 
universe innumerable suns, around each of which whirl 
dark little worlds like our own. The thought is irresistible 
that many of these, too, must contain great seas, rivers, 
and broad expanses of water glittering in the light of suns 
that we have never seen. If this be so, and there seems no 
reason why we should doubt it, the mass of water which 
occurs on the earth, vast as it appears to us, vanishes 
altogether in comparison with the inconceivably greater 
quantity disseminated through the depths of space. 

We have every reason to believe that there is now con- 
siderably less water upon the surface of the globe than there 
was formerly. The seas have probably been steadily 
shrinking for ages, and may ultimately disappear altogether 
from the earth, as they have already done in the case of the 
moon. The reason of this is that the minerals of the earth's 
crust are continually absorbing water from the ocean. 

" Water," says Milton, the author of " The Stream of Life," 
" penetrates into everything. . . . Nearly all the earths, 
flint, lime, alum, magnesia, and clay are pervaded by its 
influence. All soils, even the hardest, contain water in 
abundance, few having less than one-eleventh, some being 
nearly half water. It penetrates into every rock, till sand- 
stone becomes so full of it that one or two million gallons 
of water can be pumped daily from a single well, while chalk 
is still fuller of water. . . . Granite is supposed to contain 
two gallons of water in each cubic yard." 

The extent to which this absorption of the waters of the 
sea by minerals has gone on is almost incredible. 

It has been estimated that more than a third of the ocean 
has disappeared already owing to this cause. The bottoms 
of the seas and lakes are leaky and allow the water to filter 
down slowly into the earth's crust. In many cases it reaches 
the white-hot regions of the interior, and is here converted 
into steam under an enormous pressure, and this plays an 
important part in causing volcanic eruptions. Most vol- 
canoes are situated near the sea or near large lakes. 

Mr. Grew, in his charming book " The Romance of Modern 
Geology," thus illustrates how the sea sinks into the earth 



V 



WATER 89 

under the enormous pressures which exist in its deepest 
parts : — 

s^ " Some years ago, when certain officers of the United States Navy 
were making ocean surveys, it was found that if hollow balls of thick 
glass were sunk to great depths in the ocean, they came up more or 
less completely filled with water in proportion as the depth increased, 
though no breakage or cracking of the glass had occurred, and no 
holes in it could be discovered even by the best microscopes. In 
other words, it became evident that water had been slowly but bodily 
forced through the thick walls of the glass (under a pressure of less 
than 15,000 lb. to the square inch) in less than an hour's time. 
Evidently, then, even such a substance as glass will be penetrated by 
water if the pressure is great enough. ... In deep places (of the 
ocean) the pressure of the sea water (on the ocean bottoms) is very 
great, sufficient to force water through glass. Obviously most 
of these bottoms will leak, and leak at a rapid rate under the enor- 
mous pressure operating in the greatest depths of the sea. . . . To 
see how effective the pressure arising from the depths of the ocean 
may be in driving water into the crust of the earth, we may observe 
that the tendency to penetrate it is everywhere proportional to the 
depth of the sea. . . . Now some of the ocean depths exceed five 
miles, the greatest, near Guam, being 5,289 fathoms, almost exactly 
six miles. Is it any wonder that the deeps east of Japan, near the 
Aleutian Island, west of South America, near Guam, between Samoa 
and New Zealand, give rise to enormous leakage of the sea bottom, 
and consequently many world-shaking earthquakes ? . . . What 
may be expected of a constant water pressure which will throw a 
jet five miles high ? Such is the pressure all over the bed of the 
Tuscarora Deep, and it continues from year to year, century to 
century. It is this pressure which forces the water so rapidly into 
the earth, and gives rise to all the great earthquakes and sea-waves 
with which Japan is afflicted. No stone on earth, however thick 
its layers, could withstand such a pressure ; nay, under it the water 
would go through the hardest metals, and sink down deeper and 
deeper into the bowels of the earth. Thus subterranean steam 
would arise beneath the crust and accumulate till relief was afforded 
by a shaking of the earth." — (" Romance of Modern Geology," by 
E. S. Grew, 1909, pp. 182, 189, 190. Quoted by the courtesy of Seeley 
& Co.). 

The white-hot interior of the earth, which begins twenty 
to forty miles down, presents an insuperable bar to the further 
diffusion of water. When the liquid reaches this limit it 
is expelled again as steam or gas. 

If the whole interior of the earth were to become cool 
suddenly, its waters would begin to sink rapidly into it, 



J> 



90 MODERN CHEMISTRY 

just as they would into a mass of blotting paper or into a 
loaf of bread, and in a very few centuries its surface would 
be as devoid of water as is the Sahara desert. The same face 
would overtake the air, and the whole earth would thus 
become a huge, desolate waste of airless and waterless desert, 
covered with mountains and plains silent and changeless 
like those of the moon : 

" Where never creeps a cloud or moves a wind, 
Nor ever falls the least white star of snow, 
Nor ever lowest roll of thunder moans, 
Nor sound of human sorrow mounts to mar 
Their sacred, everlasting calm."* 

It is thus the earth's internal heat which, so to speak, 
keeps it alive on its outer surface. 

In earlier ages this zone of white-hot rock was much nearer 
the surface than it is now, and consequently the waters which 
have retreated within the earth's crust then filled the early 
seas to overflowing. Indeed, probably no land whatever 
appeared above the surface of the ocean, and the whole earth 
was one great waste of moving waters. Even so recently 
as the carboniferous era great plains existed periodically 
inundated with water to the depth of only a few inches or 
feet. Sometimes these districts were as broad as modern 
France. Naturally they turned into huge tangled swamps 
choked up with a luxuriant and gigantic vegetation whose 
decayed remains constitute our coal. It is only now, after 
ages of steady shrinkage, that the seas keep strictly to the 
limits assigned to them. 

Water enters very intimately into the constitution of 
living matter. " Of the human frame," says a writer 
of the last century, f "water forms so large a part 
that the most thoroughly smoke-dried old crone who 
ever ran the risk of being burnt for a witch would 
shrink visibly if all the water were drawn off from her 
withered frame. A gentleman of comfortable dimensions if 
distilled quite dry would be transformed into a respectably 
dressed mummy, and the famous Daniel Lambert (who 

* Tennyson, " Lucretius." f " Stream of Life," p. 566. 



WATER 91 

weighed 53 stone at the time of his death, was nine feet four 
found the body, three feet round the leg, and could carry five 
hundredweight with ease) under this draining process would 
have dwindled to the weight of a small young gentleman in 
knickerbockers. . . . Every day of his life man throws out 
by his skin and lungs quite two pounds of water. With- 
out water he could not bend a muscle or feel by a nerve ; 
the atoms of every bone are dissolved or diffused in water 
before being built up. All tissues owe their flexibility to 
water, of which they contain at least four-fifths, mechanically 
or vitally, not chemically, combined with the animal matter, 
which deprived of its water becomes wholly insusceptible 
of vitality." 

Plants, too, contain equally large amounts of water. 
Water plants often contain 95 to 98 per cent, of it, and land 
plants 50 to 70 per cent. 

We may well inquire at this stage what is there peculiar in 
water which thus causes it to enter so largely into the consti- 
tution of living matter ? The chemist will answer : Nothing ! 
Neither chemically nor physically is there anything which 
inherently distinguishes water from hundreds of other 
liquids. Every property exhibited by water is shared, to 
a greater or less extent, by many other liquids. 

The reason why water enters so largely into the constitu- 
tion of living matter is probably due to the accidental circum- 
stance that it is extremely abundant and at one time covered 

v the whole earth. 

-^ It is always very futile to speculate upon subjects, such 
as the nature of life, about which nothing is definitely known ; 
yet we cannot help suspecting that the enormous amount of 
water in living matter is due to the fact that our present 
forms of life all originated in the fluid sea and thence spread 
to land. In the earliest times, when the waters of the seas 
were still warmed by the internal heat of the earth, they were 
probably filled with enormous quantities of gelatinous and 
formless living matter, which floated in island-large masses, 
and covered the steaming oceans as with a viscid mass. All 
the different animals of to-day differentiated and developed 
out of such simple vital forms. " It is at least probable," 



92 MODERN CHEMISTRY 

says Scott Elliott in his charming book,* " that the first real 
plant on this world was a sea-weed or algae. In Germany and 
Austria there are certain springs in which water coming up 
from immense depths is at an exceedingly high temperature. 
These hot springs are used as natural hot baths, and have 
many interesting peculiarities. Amongst others is the fact 
that certain seaweeds or algae are found luxuriating in the 
hot water. Some of these can even live in springs with a 
temperature of 176 F. (8o° C.) ! Such algae may have 
remained living in exceedingly hot water ever since that 
long distant time, the very first of all geological periods, 
when there was no distinct separation between land and 
water, and when the waters which were below the firmament 
had not been separated from those above it." 

If life really did first originate in water it is very natural 
that living matter should have retained within it large 
quantities of the medium which first surrounded it on all 
sides. Indeed it was absolutely necessary that water should 
have been able to penetrate it freely through and through 
to every part, otherwise the organism could not have with- 
drawn from the sea its nourishment in the form of dissolved 
salts. We must remember that such early forms of life had 
no special organs for assimilating food. The food simply 
had to diffuse slowly from the sea into every part of the organ- 
ism. Even after ages of evolution probably all our food 
enters our bodies thus dissolved in watery fluids. This fact 
explains, too, why the early forms of life were gelatinous 
and not crystalline. For salts will diffuse as easily through 
an aqueous jelly saturated with water as through pure 
water itself. 

If the early seas had consisted of petroleum or alcohol, 
no doubt forms of life would have come into existence which 
contained as much of these liquids as they now contain water. 
At least there is nothing in the science of chemistry which 
opposes this supposition. 

Such considerations should teach us to be very careful 
as to how we dogmatise on the impossibility of life occurring 

* " Romance of Plant Life," p. 200 (1907). Quoted by kind per- 
mission of Seeley & Co. 



WATER 93 

under conditions absolutely different from those now 
prevailing upon the earth. Until we know what life is it is 
unscientific to decide beforehand what is possible and what 
is impossible. Life probably adapts itself to the planet in 
which it occurs, much as water adapts itself to the vessel which 
holds it. It develops in those forms of inorganic matter 
which it finds in a suitable condition ready to hand. On 
our planet it has developed in material consisting mainly 
of the elements carbon, hydrogen, oxygen and nitrogen. 
On other planets it may have developed in matter consisting 
of entirely different elements. One must not even exclude 
the possibility of life occurring in red or white-hot matter — 
though of course such living matter could not possibly be 
formed of the same elements which build up the vital matter 
which occurs upon the earth.* If this be so the enormous 
bulk of material in a white-hot or red-hot condition now 
scattered throughout the universe may not be so absolutely 
useless for vital purposes as it at present seems to be. 
" I suppose that no one now seriously maintains that a vast 
mass of matter like the sun, a mass 300,000 times greater 
than that of the earth, exists solely for the purpose of allow- 
ing that noble animal Man to live with some degree of com- 
fort ! Perhaps, after all, the main object of the universe is 
not to convert as large an amount of its material as possible 
into an animate form. There may be more important obj ects 
to be achieved than that, objects of which no man has 
ever had or can have the faintest inkling. As was remarked 
of old, there are more things in heaven and earth than are 
dreamt of in man's philosophy. 

Indeed, it is quite probable that all life is single in its 
essence, that men and all living creatures are but sharers in 
a vastly more extended scheme of cosmic action than we 
are aware of ; that we are, in fact, but portions of an 
infinite whole, of a mighty universal system comprising 
untold millions of worlds each crowded with living forms, 
the whole swiftly evolving towards ends quite as unknown 
^to us as to the lowest forms of life. Modern science has 

* See a series of papers by the author in Knowledge for 1905, 
and in Science Gossip (1900), in which these questions are discussed. 



94 MODERN CHEMISTRY 

opened out a vista of possibilities which were unknown 
to Tennyson when he penned the words : 

" Raving politics, never at rest — as this poor earth's pale history 
runs — 
What is it all but a trouble of ants in the gleam of a million 
million of suns ? " 

Few facts are more wonderful than the continual circula- 
tion of water over the surface of our planet. From the time 
the first drop of water fell upon our earth until now it has 
never ceased to circulate, changing the face of continents, 
wearing down mountains into plains, and plains into valleys. 
This circulation is maintained by the heat of the sun. The 
sun evaporates the water and causes it to rise in the form of 
invisible vapour, which then condenses to clouds and falls 
again upon the earth as rain ; thence by means of a thousand 
streams and rivulets it ultimately finds its way to the great 
ocean again. Indeed, as was long ago remarked, " The rain 
which we see descending was thawed for us out of icebergs 
which have watched the polar star for ages : and lotus lilies 
sucked up from the Nile and exhaled as vapours the snows 
that are lying on the tops of our hills." An active agent in 
diffusing vapour and in maintaining the circulation of water 
is vegetation of all kinds and especially trees — a fact which 
explains their beneficial influence upon climate. The present 
practically desert condition of countries like Babylonia and 
Northern Africa, countries once famed in ancient times for 
the fertility of their soil, is believed to be due, in part- at 
least, to the deprivation of these lands of their trees. 
-^~"A11 plants," says Scott Elliott, "contain a large per- 
centage of water. This may be as much as 95 to 99 per 
cent, in water plants, and 50 to 70 per cent, in ordinary 
land plants ; it is contained in every sort of vegetable 
substance. But there is also a stream of water or sap rising 
up the stem and passing into the leaves. On these leaves 
there are hundreds of minute openings called stomata, by 
which water escapes as water-vapour into the atmosphere. 
A single oak leaf may contain as many as 2,000,000 of these 
stomata. It is this current of sap which keeps the leaf fresh 
and vigorous ; it is also by this current that every living 



WATER 95 

cell is supplied with water and kept in a strong healthy 
condition. The amount of water used in this way is very 
great ; in four months an acre of cabbages will transpire or 
give out through its leaves 3,500,000 pints of water, and an 
acre of hops from 5J to 7,000,000. A single oak tree, 
supposed to have 700,000 leaves, must apparently have 
given off into the atmosphere during five months 230,000 lbs. 
of water.* 

Now, trees live to an immense age. Many oaks live to 
well over a thousand years. Some of the " mammoth " 
or " big " trees of California are certainly over 3,000 years- 
old. The age of the Dragon Tree of Oratava in the Canary 
Islands has been estimated by some authorities at 8,000 years, 
while others have estimated its age at 10,000 years. This 
tree, therefore, was hoary with age at the time that Homer 
was composing his songs or when Abraham was watering 
his flocks and herds ! 
fat. Now a little calculation will show that a single oak tree 
1000 years old will in the course of its existence give off 
something like 250,000 tons of water ! Some of the older 
trees may well have given off a million tons of water ! When 
one reflects upon the myriads upon myriads of trees, plants,, 
flowers, and grasses, which have been continually flourishing 
year in and year out for countless ages, and giving off water 
during the whole of this time, one can easily realise what a 
stupendous amount of water must have been thrown into 
the air by plants. Whole oceans must have been used up 
again and again by the vegetable world. 
' The great changes which take place upon our earth are 
effected, not by the great rivers and lakes, though these 
take their share in the process, but principally by the unseen 
waters. The Ganges, rushing in the flood season at the rate 
of nine miles an hour and bearing with it in its waters to the 
sea seven thousand million tons of earth, or the Mississippi, 
yearly rending away whole islands by the force and volume 
of its current, effect far less change in the course of a year 
than the innumerable tiny streams or rivulets which flow 
down countless valleys to the sea. The principal rivers do 
* " Romance of Plant Life," pp. 23, 24. 



96 MODERN CHEMISTRY 

not carry off more than one-sixth of the total rainfall 
even in tropical climates. 

Water has truly been compared to the blood and chyle 
of the body. Without it there could be no life in the sense 
that we understand the term. " Death would reign 
everywhere, silence and stillness would take the place of 
that universal movement which now characterises our earth." 
The hills would cease to be washed away, the valleys and 
plains to be disintegrated. Every stone which now lies 
loose on its surface would lie there through untold ages, 
unchanged and unmoved. 

The influence that the invisible water vapour in the air 
exerts in causing us to have an equitable and mild climate 
cannot at first be realised easily. This vapour absorbs the 
dark rays from the sun, and prevents the earth from radiating 
away its heat into space too rapidly. It thus acts as a 
blanket to the earth, preventing us from being scorched 
by the direct rays of the sun in the day-time, and from being 
-chilled by more than arctic frosts in the night-time. On the 
moon, where the sheltering action of atmosphere and aqueous 
vapour is absent, the temperature of its surface rises to about 
180 C. in the day-time and sinks to about — 250 C. at night ! 
Mutton could easily be roasted in direct sunlight there, 
while air could not only be liquefied, but actually frozen 
hard, by the intense cold prevailing at night ! 
— - -The weather, which now provides us with an unending topic 
for conversation and complaint, would cease to interest us on 
a waterless globe. There would be no rain, no snow, no hail, 
no frost. Nothing but blinding sunshine or darkest night ! 
cOne of the first questions which arises in the mind of a 
student when approaching for the first time the chemical 
study of water is this : Of what is this abundant and useful 
liquid composed ? The answer is : Of invisible gases ! Yes, 
strange as it may appear, especially when we view breakers 
rolling inwards upon the sea-shore, the whole mass of water 
in the sea is composed of the invisible gases hydrogen and 
oxygen, elements of which we will presently treat, com- 
pressed together by the mighty forces of chemical affinity 
to nearly the eighteen-hundredth part of the volume 



WATER 



37 



they occupy at ordinary temperatures and pressures. To 
do this by pressure alone would require the application of 
nearly four million pounds per square foot ! If, by means of 
some cosmic influence acting through space, the forces which 
hold the oxygen and hydrogen gases imprisoned within the 
water molecules were suddenly slackened, the oceans would 
instantly be resolved into a vast mass of highly compressed 
gas, which, with a roar like a vast thunder peal, would ex- 




Fig, 14. — If water suddenly became incompressible the sea would rise 
116 feet above its present level, and would rush over the land burying 
cities beneath its waves, 

pand, rushing upwards with an irresistible force until it 
had occupied a volume considerably greater than twice the 
volume of the whole earth, and had formed about it an 
atmosphere extending upwards for over a thousand miles ! 
Such an atmosphere would produce a pressure upon the 
surface of the globe of over three tons per square inch, a 
pressure sufficient to crush a man as he is now constituted 
into a formless pulp. 



98 MODERN CHEMISTRY 






- Water, in fact, is composed of hydrogen and oxygen united 
together in the proportion of nearly two volumes of the 
former gas to one of the latter. A cubic inch of water 
contains 1,234 cubic inches of hydrogen united to 617 cubic 
inches of oxygen, both gases being supposed to be measured 
at o° C. and 760 millimetres pressure. 

Water is at ordinary temperatures a liquid possessing a 
very faint bluish-green colour, well seen in the colour of the 
ocean and in certain lakes. Our earth, seen from outside, 
must appear as a greenish planet capped with snowy poles. 

- - Water is an almost incompressible fluid, one million vol- 
umes diminishing by only fifty when the atmospheric 
pressure is doubled. Slight as this compressibility may 
seem to us, yet, as Prof. Tait has shown, it produces most 
important results. At the bottom of the dark abysses of 
the ocean, nearly six miles deep, the pressure must amount 
to 1000 atmospheres. The result of this compression is to 
make the surface-level of the general mass of the oceans 
some 116 feet lower than it would be if the water were per- 
fectly incompressible. If water suddenly ceased to be com- 
pressible the great oceans would instantly rise 116 feet in 
height and pour in a mighty flood over low-lying lands. 
Over 2,000,000 square miles of land, something like four per 
cent, of the whole land area of the globe, would be submerged 
by the torrent,* the hills appearing above the waters as 
small islands. 

Fresh water freezes at o° C, sea-water at about — 2. 8° C. 
The fresh water in our ponds and lakes always freezes first 
upon the surface. If we dip a thermometer into the water 
below the ice we shall find always that it is warmer than the 
ice above, being about 4 C. The reason of this is as follows : 
The ordinary rule for the contraction of water is that it 
shrinks with cold and expands with heat. As water shrinks 
it becomes denser and therefore heavier, bulk for bulk. 
Consequently, when a low atmospheric temperature acts 
upon the surface of a pond or lake, the water as it is cooled 
at the surface becomes heavier and goes down. The surface 

* "Challenger" Report, "Physics and Chemistry," II. part I., 
p. 76. 



WATER 



99 



layers of cold water keep on sinking, while fresh and warm 
water, which is lighter, keeps on floating to the surface until 
the whole mass of water is cooled down to about 4 C. 
At this temperature fresh water attains its maximum density ; 
in other words a given bulk of water weighs more at 4 C. 
than at any other temperature, and so will sink to the bottom 
of the pond. On cooling below 4 C. the fresh water begins 
to expand again. The greater cold makes it lighter instead 




-.«/ 




J 



,.WATO1 SURFACE WATER. . *J"5*Gr 




Fig. 15. — Temperature of the Water of the Sea, 

of heavier. Consequently, water cooled below 4 C. floats upon 
the surface of water at 4 C, and if it is exposed long enough 
to the cold atmosphere, it will freeze and form a layer of ice 
over the surface of the water at 4 C. The case is somewhat 
different with sea-water, which contains much salt dissolved 
in it. Sea-water continues to contract right down to its 
freezing-point at about — 2.8° C. Consequently, the more it 
is cooled the heavier it becomes. The coldest sea-water, 
therefore, sinks to the bottom of the ocean, and this is the 



ioo MODERN CHEMISTRY 

reason why the dark abysmal valleys of the sea are filled with 
water as cold as, and sometimes even colder than, melting 
ice. It is only when we approach the surface that the water 
becomes sensibly warm. A curious consequence of this 
fact is that ice in sea-water begins to form at the bottom — 
not always, because when ice is once formed on the surface 
it will extend from the edge of its previous surface. Still it 
is well known among Arctic voyagers and Baltic fishermen, 
that when the season is changing and ice is about to form, 
in the first instance it comes up in little plates or discs from 
the bottom. When the fisherman in the Baltic or Norwegian 
fiords sees these little discs coming up from the bottom, 
like so many jelly fish, to float on the surface, he at once, if his 
boat is at all distant from land, makes for land directly, 
for he knows that if he remains he might be frozen up in the 
course of a few hours.* Whether ice forms in the salt seas 
or in fresh-water lakes, one fundamental fact remains, and 
that is, that ice is lighter than water and consequently floats 
on its surface. Indeed, it would be a most serious matter if 
this were not the case. For example, if ice were heavier 
than water it would, when formed, sink to the bottom ; 
hence in sharp winters ice would gradually accumulate at 
the bottom of our lakes and seas ; the heat of the succeeding 
summer would merely warm the water on the surface without 
affecting the temperature of the water below a certain depth, 
because water is such a very bad conductor of heat. In fact 
water conducts heat so badly that it is possible to place a 
piece of ice (wrapped round with lead wire in order to make 
it sink) at the bottom of a long tube containing water, and 
then boil the water at the top without melting the ice at the 
bottom I Hence, as winter succeeded winter the layer of ice 
at the bottom of our seas and lakes would gradually increase 
in thickness until all our seas, lakes, and even the mighty 
oceans themselves, would be converted from top to bottom 
into vast masses of ice. 

All that the heat of the summer could do would be to melt 
the superficial ice through a few feet, thereby converting 

* Dr. Carpenter's " Science Lectures for the People," 2nd Series, 
1870-71, pp. 116, 117. 




WATER loi 

the seas into vast shallow morasses, with deep crevices here 
and there. In winter all would be frozen over again. Nothing 
could live in such a sea. Fishes would be unknown except 
in regions that we now deem tropical. Our climate would be 
arctic in character. Northern Europe would be an unknown 
land, covered over with vast glaciers and perpetual snow ; 
it would present much the same appearance that the cold, 
desolate continent about the South Pole presents to explorers 
at the present time. The sites of world-cities like London, 
Paris, Berlin, would be occupied by ice-clad plains swept by 
cold winds and snow-storms. The centre of civilisation 
would shift from lands like Europe and Northern America 
to tropical lands like India, Africa, and Central America, 
which, however, would under the new conditions enjoy a 
quite temperate climate. 

Who would have thought that the apparently unimportant 
property that water possesses of slightly expanding when 
freezing would have exerted such an astonishing influence 
upon our world and on civilisation ? 

At the moment of freezing the water increases in 
volume and in so doing exerts a very great pressure. 
Now soils and rocks are all porous and suck up large 
quantities of water. A frost comes and this water freezes, 
forcing the particles apart. The soils on thawing are thus 
powdered. Water freezing in the innumerable cracks be- 
tween rocks drives them asunder. Gradually, with each 
succeeding winter, the rifts in the rocks grow wider and wider, 
until ultimately the rock splits in pieces, and goes thundering 
down into the valley below. At Spitzbergen and on the 
coast of Greenland great rocky cliffs are being continually 
demolished from this cause. 

Water under ordinary atmospheric pressures freezes at 
o° C. But under great pressures it will not freeze even at 
low temperatures. Thus, if subjected to a pressure of 13,000 
atmospheres water freezes at — 18 C. Conversely, great 
pressures will turn ice into water. Thus if a mass of ice, 
cooled to a very low temperature and subjected to the very 
great pressure of 13,000 atmospheres, be allowed to gain 
heat, it melts when the temperature reaches — 18 C. The in- 



102 



MODERN CHEMISTRY 



stant the pressure is released the water at once freezes 
again, for it is only the pressure which preserves the water 
in a liquid form below o° C. These facts acquire a great 
importance in northern regions. The whole of the regions 
around the North and South Poles are vast snow-fields some 
miles deep. Think of falling into an abyss two miles deep ! 
Yet there probably occur rifts and cracks in the ice which 
descend to such vast depths. These cracks form as the 

result of a slow but per- 
petual movement of the 
ice under its own weight ; 
and this movement seems 
itself to depend upon the 
fact that under the huge 
pressure exerted by the 
ice above, the ice in the 
depths melts and the 
whole mass thus becomes 
mobile, flowing from the 
hills and mountains slowly 
down to the sea. These 
great rivers of ice are 
called " glaciers." They 
occur in all parts of the 
world where the mountains 
are high enough. The 
more rapid travel four feet 
in an hour, the slower ones 
only a few inches a day or 
perhaps a week. We must not think of these vast masses 
of ice as formless. No, every fragment of ice possesses a 
wonderfully intricate and beautiful internal structure, being 
composed of myriads of molecules all definitely arranged in 
space and all whirling, like little spinning tops, at a tremendous 
rate ^ This beautiful internal structure of ice may be revealed 
to the eye by allowing a beam of sunlight to pass through a 
block of ice by means of a lens. Suddenly there flashes into 
view throughout the interior of the previously apparently 
formless ice, a large number of little geometrical six-sided 




Fig. 16. — Snow Crystals. 



WATER 



103 



Steam. 



Jr2vuriJbl& 
Stress* efSl&stm. 



hoi enovLo/7 



stars, partially vacuous because the ice contracts in volume 
when melting to water. The beautiful crystals seen when 
snow is examined under a microscope give further evidence 
of the wonderful internal structure of frozen water. A 
fragment of ice the size of a pin's head contains a million 
million million molecules all definitely arranged and rotating 
in parallel directions. Such a tiny speck of ice, therefore, 
contains a hundred thousand million times more molecules 
than there exist visible 
stars in the whole uni- 
verse ! How enormously 
vast a universe of mole- 
cules, then, must be one 
of the huge icebergs float- 
ing in the sea ! And our 
wonder grows when wc 
reflect that these icebergs, 
vast as they are, form only 
an insignificant part of the 
whole mass of similarly 
constituted ice which 
clothes our Poles eternally 
with a garment of dazz- 
ling whiteness. 

Under ordinary atmos- 
pheric pressures water 
boils at ioo° C, passing 
into an invisible gas or 
vapour called steam. It is only when this invisible 
vapour cools below ioo° C, that it condenses to a multitude 
of tiny drops of water. The white clouds which form 
around steam jets and which float in the sky are formed 
of these tiny drops. True steam is invisible. This 
may be shown by means of the following very remark- 
able experiment. A jet of ordinary steam from a boiler is 
passed through a copper pipe heated to a low red heat (Fig. 
17). The issuing steam is so hot that it does not, like an 
ordinary steam jet, condense to a visible white cloud. Its 
temperature is so high that it cannot condense at all to the 




Fig. 



17. — Production of Superheated 
Steam. 



104 MODERN CHEMISTRY 

droplets of water which form a steam cloud. Instead, it 
mixes with the air and then dissolves clear in it. Conse- 
quently, such a stream of steam is quite invisible. Its 
presence, however, may be made manifest to the eye by 
holding in its path a bit of paper. So fierce is the heat it 
possesses that the paper is seen to char as in a fire. 

In many planets all the water is in this superheated gaseous 
state ; and once upon a time it was also in this state upon 
our own earth, as we have already seen. Hence we see 
that although we always regard water as a liquid, yet, if we 
had happened to live under conditions somewhat different 
from those now reigning upon the earth, water might have 
been known to us only in the form of a gas or a solid, and 
we could not have failed to form entirely different notions 
of its properties from those that we now hold. For example, 
if the planets Jupiter, Saturn, and Neptune were inhabited 
by a race of intelligent salamanders, to whom a bright red 
heat was a pleasant degree of warmth, then, to these truly 
hot-blooded creatures water as a liquid would be quite 
unknown. For, the surface of these planets being probably 
red hot, they could only know it in the form of a gas, quite 
invisible to the eye, and presenting much the same properties 
to them as air does to us at ordinary temperatures. 

The pressure of aqueous vapour or steam increases with the 
temperature. Thus at o° C. it equals the pressure of a column 
of quicksilver 4.6 mm. high. At ioo° C. it balances 760 milli- 
metres of mercury, or the pressure of our atmosphere. At 
370 C. the pressure of steam is 196 atmospheres, or i£ tons 
per square inch ! Now water boils when the pressure of its 
vapour equals the pressure on its surface. Water, therefore, 
can be made to boil at almost any temperature by merely 
altering the pressure on its surface. Thus, if the pressure 
on its surface is only 4.6 mm. — say the pressure inside the 
bell jar of a good air-pump — the water will actually boil at 
the temperature at which it freezes, viz. at o° C, for at this 
temperature the pressure of steam is 4.6 mm. At ioo° C. 
the pressure of steam just balances the pressure of the atmo- 
sphere at the sea-level, and this is why water under ordinary 
conditions boils at ioo° C. At a temperature of 370°C. the 



WATER 105 

pressure of steam amounts to nearly 196 atmospheres. Con- 
sequently, when subjected to this great pressure water will 
boil at 370 ° C, that is to say, almost at a red heat ! Several 
important natural consequences arise from these facts. Thus 
down at the bottom of the ocean, where the pressure often 
amounts to over a thousand atmospheres, the water would 
not boil even at a low red heat. It could, therefore, rest 
upon a red-hot sea-bottom without explosively turning into 
steam. Again, on the tops of high mountains, where the 
atmospheric pressure is low, water boils considerably 
below ioo°C. At the top of Mont Blanc it boils at 86.4 C. ; 
on Mount Everest it boils at about 70 C. Water boiling at 
this temperature would hardly cook an egg ! 

On a planet such as Mars, where the atmosphere is light 
and thin, water would boil at the temperature of the blood ; 
while on the moon, where the mountains jet up sheer into 
an absolute vacuum, water would boil below the melting 
point of ice ! Ice on the moon would sublime without 
melting, just as camphor does under ordinary temperatures 
and pressures. 

We must now say a few words about the curious effect a 
high temperature produces on the properties of water. Let 
us imagine the reader to be transported for a short time to 
that early period of the world's history when the seas which 
now cover her were just beginning to be deposited. The 
atmospheric pressure at that time was hundreds of times 
greater than it is now, and consequently, the waters of those 
early seas would not boil, as they now do, at ioo°C, but at 
a far higher temperature. The earliest seas of our planet 
may have possessed a temperature anywhere between 
300-370 C. Indeed, at the present time many planets 
must exist which are covered with seas of such intensely 
hot water. The highly heated and compressed water which 
occurs deep down in the interior of the earth is in just the 
same condition now as the early seas of the earth were once. 

Such highly heated and compressed water, however, 
presents properties entirely different from those usually 
associated with this useful and harmless liquid. Under such 
circumstances it becomes one of the most corrosive substances 



106 MODERN CHEMISTRY 

known, acting in many ways like a strong acid such as diluted 
oil of vitriol. As we shall see in a later chapter such intensely 
hot and compressed water will dissolve metals like iron and 
zinc with effervescence, just as a strong acid will, evolving 
hydrogen gas. 

Even such an insoluble substance as glass dissolves 
in it as freely as sugar in tea. It is just as well, therefore, 
that we do not live in such times, for we should certainly 
have had to do without such articles as glass tumblers and 
iron kettles ! " At ordinary temperatures," says Geikie,* 
" water is a very weak base or acid. At i8° it is about ioo 
times weaker than silicic acid. But by increase of tempera- 
ture the relationship of the tw r o bodies is completely changed. 
At about 300 C. it is estimated that water and silicic acid are 
equally strong, but at 1000 C. water is some 80 times, 
and at 2000 C. about 300 times stronger than that acid. . . 
Water at 1000 and 2000 C. will act as a powerful acid." 

There is nothing really very surprising in this when we 
remember that all liquids which are strongly acid at ordinary 
temperatures become quite neutral at low temperatures. 
A decrease of temperature reduces acid properties while 
an increase of temperature increases them. For example, 
the strongest mineral acids which we are acquainted with, 
such as sulphuric, hydrochloric, and nitric acids, all most 
intensely corrosive substances at ordinary temperatures, 
become at — 105 C. quite neutral substances. 

Water, in fact, is in just the same condition at ordinary 
temperatures as these acids are at low temperatures. All 
that is required in each case to bring out acid properties is 
an increase of temperature. 

* " Textbook of Geology," p. 356 (1903). 



CHAPTER VI 

THE ELEMENT HYDROGEN 

It is difficult to describe the further wonders of chemical 
changes without making the reader familiar with some of 
the substances which take part in them. We will therefore 
begin by giving a description of the simplest of all the 
substances known upon the earth, that is, the element 
hydrogen. 

Nearly four hundred years ago the famous alchemist 
Paracelsus observed that when metals like iron or zinc 
were placed in sour or acid liquids, like vinegar or diluted 
" oil of vitriol/' the metal gradually dissolved and at the 
same time bubbles of a gas were seen to rise through the 
liquid. This gas rose exactly like ordinary air, but was 
distinguished from it by the fact that it caught fire and 
burnt when a light was applied to it. On account of this 
it was known for long as " inflammable air," but we now 
know it is nothing but the element " Hydrogen." The 
apparatus usually used for preparing the gaseous hydrogen is 
shown in Fig. 18. The bottle A contains fragments of iron 
or zinc ; acid diluted with water, say sulphuric acid, is poured 
down the glass funnel C on to the metal, and the gas as it 
comes bubbling up through the liquid is led off through the 
glass tube into the bottle B, which has previously been 
filled with water, and inverted over the same liquid con- 
tained in a basin. The gas bubbles up through the water 
and is thus easily collected. The mechanism of this action 
is chemically a simple one. All acids contain loosely held 
hydrogen, and indeed they owe their sourness and other 
distinctive properties to this fact. Many metals dissolve in 
acids and in so doing expel the hydrogen from the acid and 
occupy its place in the molecule. For example, in the case 

107 



io8 MODERN CHEMISTRY 

of iron or zinc and sulphuric acid the chemical changes are 
expressed by the equations : 

Zn + H 2 S0 4 = ZnS0 4 + H 2 ; 

Zinc Sulphuric Zinc Hydrogen 

Acid Sulphate Gas. 

Fe + H 2 S0 4 = FeSO, + H 2 

Iron Sulphuric Ferrous Hydrogen 

Acid Sulphate Gas. 

This is an experiment familiar to the merest tyro in 
chemistry. Almost every schoolboy has prepared hydrogen 
at some time or other by this method ; yet how few of those 
who have performed this experiment dozens of times have 
realised the mystery and wonder of the process that is 
going on under their very eyes ? How few realise as they 
watch the zinc or iron dissolve in the acid and the countless 
bubbles of gas arising merrily through the liquid, that they 
are witnessing a veritable molecular catastrophe ? Yet this 
is so. As we have seen in a previous chapter all chemical 
reactions are to the atoms tremendous catastrophes. The 
liquid that we see in the bottle really consists of countless 
millions of tiny molecules, tiny planetary systems of atomic 
dimensions, each pursuing its own individual course in the 
liquid, a course so charged with events and changes that in 
the millionth part of a second, a span of time so small 
as to be absolutely beyond our consciousness, each one of 
these little molecules has lived through an age, has survived 
millions of collisions with other molecules, has been trans- 
formed, shattered and re-formed, thousands upon thousands 
of times. Each sulphuric acid molecule consists of a central 
sulphur atom to which are attached four oxygen and two 
hydrogen atoms, each rapidly swinging round a tiny orbit 
in the molecule, and when this system collides with the atoms 
of zinc or iron, the ensuing shock sends the rapidly moving 
hydrogen atoms flying off into space, and we see them arise 
as ?n innumerable number of tiny bubbles through the liquid, 
each bubble itself a vast array of billions of atoms of this 
gas. The metallic atoms take the place of the hydrogen 
atoms in the sulphuric acid molecule and thus produce the 
salts, zinc or iron sulphates. The action, however, is really 
much more complicated than this. It is attended with th 



THE ELEMENT HYDROGEN 



109 



development of electricity and with other phenomena, 
which, however, we cannot stop to discuss here. Indeed, 
though the chemical equation expressing the change is simple 
enough, the real complexity of the process is probably 
immeasurably greater than anything of which we have any 
conception. The ceaseless collisions going on all this time 
between the sulphuric acid molecules and the zinc atoms 
naturally set up violent motions among the molecules, 




Preparation of Hydrogen. 



and this increased ^motion manifests itself as heat. The 
solution becomes quite warm to the touch. 

Many other methods of preparing hydrogen exist, but we 
will mention no more than two. We saw in the last chapter 
that water contains hydrogen combined with oxygen. Now 
many metals will decompose water, combining with its 
oxygen and setting free its hydrogen. Some metals (such 
as sodium, potassium, calcium, etc.) do this at ordinary 
temperatures, but others, such as iron and zinc, require to 



no MODERN CHEMISTRY 

be heated. Thus if steam be blown through a red-hot pipe 
packed with iron filings, hydrogen gas will issue at the end 
of the tube and may be collected over water in the ordinary 
way. The water has been decomposed according to the 
equation : 

3Fe + 4 H 2 = Fe 3 4 + 4H2 

Iron Wafer Black Iron Oxide Hydrogen 

In the past disastrous explosions have been caused in 
iron smelting works by allowing the white-hot iron from 
the furnace to flow directly into water, either intentionally 
with the object of cooling it rapidly, or accidentally. Large 
volumes of hydrogen have thus been evolved, which mixed 
with air forms an explosive mixture. The evolved gas 
coming into contact with the white-hot iron has then 
exploded, blowing scalding water and molten iron in all 
directions, and killing or wounding all who were near. Quite 
a short time ago an explosion due to this cause occurred in 
an iron works at Wolverhampton. A great blast furnace 
was in action and all was going on quietly when suddenly a 
thunder-like explosion took place underneath the mighty 
structure, and with a mighty roar there burst forth smoke 
and flame and flying fragments of fractured masonry. 
The molten metal at the bottom of the furnace had 
leaked into a small quantity of water flowing along a 
channel which discharged from the tuyeres, and the water, 
being instantly decomposed, produced a large volume of 
gas, which, exploding, shattered the bottom of the furnace 
and allowed no less than twenty-five tons of molten dazzlingly 
white-hot metal to rush tumultuously forth from the frac- 
tured furnace and demolish in its fury an adjacent building. 
Six men were working in the neighbourhood, and without 
a moment's warning they were hurled in all directions, 
while at the same time they were enveloped in a cloud of 
flying debris of white-hot molten steel, boiling water, 
masonry, and dust, and all were more or less badly injured. 
Indeed had the men. happened to have been nearer to the 
furnace they could hardly have escaped total destruction. 

At the present time masses of iron are cooled by spraying 
water upon them by means of a hose. In this case sufficient 



THE ELEMENT HYDROGEN in 

gas is never evolved at one time to cause danger. In the 
case of impure zinc the same action takes places rapidly 
even in boiling water, according to the equation : 

Zn + H 2 = ZnO + H2 

Zinc Water Zinc Oxide Hydrogen 

This fact may at first strike the reader as being of little 
interest or importance, and yet, so intimately is chemistry 
connected with our daily life, it has been attended with 
tragic consequences at least once. A few years ago some 
workmen while constructing a boiler carelessly left inside it 
some fragments of zinc, little dreaming that by so doing 
they would cause the death of so many fellow creatures and 
plunge so many happy families into mourning. In due 
course the boiler was hoisted upon a German war-ship and 
riveted down. 

Some months afterwards the vessel went out on her trial 
trip. The hold was filled with busy stokers, and the great 
engines throbbed, driving the mighty vessel swiftly through 
the sea. All this time the water was heated in the boiler 
to an exceedingly high temperature and the zinc was 
dissolving rapidly in it, giving off a large amount of hydrogen 
gas. This mingled with the air in the boiler to form a terribly 
explosive mixture, and so all unknown to the men working 
around, the great boiler was gradually filled with the deadly 
gaseous mixture. Suddenly, without a moment's notice, 
with a blinding flash of light and a roar like an enormous 
thunder peal, the great boiler blew to pieces, killing or 
maiming all the men in the room and filling the vessel 
with a cloud of scalding steam. The cause of the explosion 
remained a mystery until some days afterwards the tell-tale 
fragments of zinc were found in the boiler. Thus we see 
that the forces of chemical affinity, which under control 
make so useful a servant, out of control make a terrible 
master. Hydrogen may also be obtained by passing an 
electric current through water which has been acidified 
with a little sulphuric acid. The electricity decomposes the 
water, hydrogen coming off at the negative and oxygen at 
the positive pole according to the equation : 



H2 MODERN CHEMISTRY 

2H a O = 2H 2 + O a 

Water Hydrogen Oxygen 

Solutions of many salts in water will decompose in much 
the same way. Indeed great industries, employing thousands 
or workmen and millions of money are founded upon this 
property of the electric current. 

To the thoughtful mind there are few substances which 
arouse such interest as this invisible gaseous element. It is 
the lightest substance that occurs upon the earth (though 
probably there exist lighter elements in space) and as such 
has been the object of much attention and speculation. 
For many years it was believed that it formed the basis of 
all the elements, an idea first put forward by a chemist 
named Prout in 1 8 15. He held that all the other elements 
were merely condensations of hydrogen atoms, and that 
consequently their atomic weights were all exact multiples 
of that of hydrogen. 

The attempt to prove or disprove this idea has led to some 
of the most careful and magnificent research work that the 
world has ever seen. It occasioned the splendid atomic 
weight determinations of Stas, Dumas, Marignac, and others 
too numerous to mention. It filled chemistry with a mass of 
new data and inspired chemists with a dream of the chemical 
unity of all matter, an idea which, in its original form at 
least, has now been proved to be untenable. The atomic 
weights of all the elements are not exact multiples of that 
of hydrogen, although in many cases they are nearly so, and 
the nearness in the approach to whole numbers is far too 
close to be explained by accident or coincidence. The 
doctrine of the unity of matter is, of course, a very ancient 
one, dating back to the earliest dawn of civilisation in the 
East. Indeed it may ultimately be proved that 

" All things the world which fill 
Of but one stuff are spun." 

Even to-day many chemists, with a considerable show of 
reason, believe in a modified form of Prout's hypothesis. 

The mystery which surrounds this wonderful element is 
increased when we turn to the heavens and study the chemi- 
cal constitution of the stars. We find that hydrogen has 



THE ELEMENT HYDROGEN 



ii3 



an enormously wide distribution. We find it everywhere 
in space, no matter to what part of the sky we turn our 
eyes. We find it in every nebula, often in vast masses which 
stagger the imagination by their seemingly infinite extension. 
All stars contain it, some of the hotter ones being almost 
entirely composed of it. Our own sun contains an incalcul- 
ably great quantity of it. On his surface may be seen vast 
flames of hydrogen which sometimes rush up in stupendous 
columns to the height of hundreds of thousands of miles. 



Earth 




Fig. 19. — Vast hydrogen flames observed on the sun's surface by 
Prof. Young in 1871. The flames were 100,000 miles long and 
54,000 miles high. The size of the earth is shown for comparison. 



In 1 87 1 Professor Young observed some vast flames on the 
sun's surface which were 100,000 miles long and 54,000 miles 
high. In 1880 Langley saw some tower aloft to the height of 
over 350,000 miles ! Such flames are hundreds of thousands 
of times greater than our whole earth, and yet astronomers 
assure us that these are nothing to some of the flames which 
occur on many of the suns of space ; for some of 
these are millions of times larger than even our own sun, 
gigantic as he seems to us, suns largely composed of hydro- 
gen, of the very same hydrogen gas that we see arising from 
zinc and acid, but in a very different condition. For on 
such bodies the hydrogen is compressed by its own weight 



H4 MODERN CHEMISTRY 

until it is more rigid and solid than steel, and heated to such 
a high temperature that it glows and gives forth an im- 
mensely fierce light ; there it is torn up by volcanic concus- 
sions of an unthinkably vast force, and hurled aloft in mighty 
flames to the height of a million miles and more ! Even on 
our own sun hydrogen flames and torrents of heated gas 
rush in mighty cyclones over its surface at the rate of more 
than 400 miles a second ! 

Hydrogen is present always, not only when worlds are 
about to form, but also when they explode. 

" In the youngest stars," says Le Bon,* " that is to say, 
the hottest, there hardly exists anything but a few gases, 
principally hydrogen ; then as these stars become cooler, 
there successively appear the simple bodies we know, 
beginning with those of the lowest atomic weight. . . 
Spectrum analysis shows that these stars are at very 
different stages of evolution. Their past must be of 
fearful length, since geologists estimate the existence of our 
planet at several hundred million years. During these 
accumulations of ages unknown to history, the millions of 
stars with which space is peopled must have begun or ended 
cycles of evolution analogous to those now pursued by our 
globe. Worlds peopled like ours, covered with flourishing 
cities filled with marvels of science and of the arts, must have 
emerged from eternal night and returned thereto without 
leaving a trace behind them. The pale nebulae (which as 
we have seen consist largely of hydrogen) represent 
perhaps the last vestiges of worlds about to vanish into 
nothing or to become the nuclei of a new universe. . . . 
We may ask ourselves whether the end of a universe by a 
sudden explosion after a long period of old age does not 
represent its most general ending. These abrupt annihila- 
tions manifest themselves in the sudden apparition in the 
heavens of an incandescent star, which pales and vanishes 
sometimes in a few days, leaving generally no trace behind 
it, or at most a faint nebula (which is always rich in 

* Le Bon, "The Evolution of Forces," pp. 83-93. Published by 
Kegan Paul, Trench, Triibner and Co. ; quoted by the courtesy of the 
publishers. 



THE ELEMENT HYDROGEN 115 

hydrogen). When the new star first appears, its spectrum, 
at first analogous to that of the sun, proves that it contains 
metals similar to those of our solar system. Then in a short 
time, the spectrum is transformed, and becomes that of the 
planetary nebulae — that is, it only contains rays of a few 
simple elements (like hydrogen) some of which are unknown. 
It is therefore evident that the atoms of the temporary star 
have been rapidly and profoundly transformed. . . . These 
transitory stars, resulting no doubt from the sudden explo- 
sion of a world accompanied by the disintegration of its 
atoms, are not rare. Hardly a year passes without some 
being observed, either directly or by the study of photo- 
graphic plates. One of the most remarkable was the one 
recently observed in the constellation of Perseus. In a few 
days it attained a brilliancy which made it the most brilliant 
„ star in the sky ; but twenty-four hours later it had begun to 
pale, its spectrum was slowly transformed, and became, as 
before said, that of a planetary nebulae — an evident proof, 
I repeat, of atomic dissociation. At the very moment 
when this transformation was taking place, photographs of 
long exposure showed nebulous masses round the star, 
produced no doubt by atomic dissociation, which rapidly 
left it behind at a speed of the order of light — that is to say, 
analogous to that of the Beta particles emitted by radio- 
active bodies when dissociating. The astronomers were, 
then, enabled to be present at the rapid destruction of a 
world." 

The words in brackets are inserted by the author. Chemists 
and physicists are by no means agreed as to the correctness 
of this explanation of the facts given by Le Bon. ;There 
seems, however, little doubt that worlds do disappear 
suddenly, and in their place appears after a time a thin wisp 
of incandescent hydrogen and other light gases. So that 
hydrogen is undoubtedly connected with the great problems 
of the evolution of matter and of the universe. It is this 
fact which makes the study of this gas so supremely inter- 
esting. That hydrogen does actually occur in space, and that 
the spectroscopic observations of scientists are no mere 
chimerical theoretical deductions, we have a very tangible 



n6 MODERN CHEMISTRY 

proof ; for a visitant from one of these hydrogen worlds 
actually fell upon our earth, and was analysed by Graham 
in 1867. This visitant was a piece of meteoric iron from 
Lanarto in Hungary. It was found to contain 2.85 times its 
volume of hydrogen. This shows that the iron had come 
from a planetary atmosphere containing hydrogen probably 
under a pressure far greater than that of our own atmosphere. 
Was this fragment a piece of some world which had been 
destroyed by a vast explosion or collision such as that which 
destroyed the star in Perseus ? Had it been hurled with 
incredible force far from a flaming world into the depths 
of space, and after ages of wandering finally reached our 
world ? Or was it but an aggregation of cosmic dust culled 
from all parts of the universe ? No answer can ever be 
given now to these questions. 

When endeavouring to estimate the amount of hydrogen 
which occurs in space we must remember that we are able 
to perceive this substance only when it is in a strongly excited 
and luminous condition. This is probably an entirely 
exceptional condition of matter. There must exist in 
space dark masses of hydrogen incalculably vaster than 
any of the luminous masses of which we are aware, and yet 
the quantity of hydrogen visible in the heavens is so great as 
to defy all calculation and all conception. No matter to what 
part of the heavens we turn we see it flaring there. This 
universal presence of hydrogen throughout the whole universe 
betokens that it plays some important part in building up the 
giant fabric. What this part is we do not know. As we have 
already mentioned, though no proof is forthcoming, it is 
suspected of being the fundamental element from which the 
others are derived. No doubt in the course of time a fuller 
light will be thrown upon this and other allied problems. 

We need not look only to the heavens, however, to find 
hydrogen. We find it in plenty on the earth. Nearly one- 
ninth of the weight of all the vast masses of water on the 
globe are composed of this gas. How many billions of tons 
this amounts to, I am sure I cannot say. It must be at 
least a million billion tons. Hydrogen also occurs, though 
only in very small quantities, in our atmosphere, 



THE ELEMENT HYDROGEN 117 

The very small quantities which do occur have probably 
been belched out from volcanoes, as it is found in the 
gases evolved from them ; but it also comes out of the 
earth in some places. Thus in the salt mines at Stassfurt 
it sometimes comes streaming forth in a very pure condition 
and under quite a strong pressure from cracks in the carnal- 
lite. It is found, too, mixed with other gases, in the gas 
wells which occur in Russia and America in oil-bearing 
districts. Curiously enough it is also evolved in very small 
quantities in the gases breathed out by plants. From all 
these sources it gets into the air. It has been suggested 
by Liveing, however, that it also diffuses in from the depths 
of space ; for as we have just remarked very large amounts 
of hydrogen occur scattered in space, and as the sun with 
the planets rushes onwards with a velocity of nine miles a 
second towards an unknown destination, some of this 
hydrogen may well be caught in the earth's atmosphere. 
However, free hydrogen could never accumulate in very 
large quantities in the earth's atmosphere ; for as Dr. John- 
stone Stoney pointed out long ago, the attraction of gravity 
is not sufficiently strong to keep particles moving so rapidly 
as hydrogen molecules from gradually flying off into space. 

Few chapters of science are more interesting, and at the 
same time few so rich in tragic incidents brightened only 
by the heroic courage and intrepidity displayed by the 
investigators, as that which tells of the attempts of man to 
attain dominion over the air and to explore its upper regions. 

On account of its extraordinary lightness hydrogen gas 
has been largely instrumental in securing the success that 
has been achieved. The gas is nearly fourteen times lighter 
than air. It pours upwards through the air in much the same 
way that a cork rises through water. One cubic metre of 
hydrogen gas will lift 1.2 kilogrammes from the ground ; 
or in English measure, one cubic yard of gas will carry a 
weight of three pounds. 

It is no wonder, therefore, that this gas was employed for 
inflating balloons very soon after their invention. The 
first balloon ever rilled with hydrogen gas ascended into the 
air at Paris on August 27, 1783. A young professor of 



n8 MODERN CHEMISTRY 

physics, Charles by name, having heard that the brothers 
Montgolfier had succeeded in causing balloons to ascend 
filled only with hot air, conceived the brilliant idea of using 
hydrogen instead which has an immensely greater lifting 
power. Assisted by the brothers Robert, Charles carried 
out his first experiment at the Champ-de-Mars, and on 
December I they undertook an aerial voyage. The arrange- 
ments devised by Charles are those still in use. The balloon 
is of strong silk coated with a layer of indiarubber varnish ; 
its upper half is covered with netting, from which hang 
cords, to whose lower extremities is attached a wicker 
basket. In the latter are placed small bags of sand serving 
as ballast, and below it hangs a grappling hook. Ordinary 
coal gas has sometimes been substituted for hydrogen, 
although being much heavier it is not so effective. 

The height to which such balloons will rise is very great. 
Thus Gay Lussac attained in 1804 a height of 23,000 feet, or 
over four miles ; Barral and Bixio attained in 1850 a height 
of 24,000 feet, while Glaisher and Coxwell attained in 1862 
the greatest height ever reached, that of between 36,000 
and 37,000 feet, and at which the barometer only marked 
7 inches as compared with 29.6 before starting. Strange 
indeed must have been the sensations experienced by these 
first voyagers. They had only to look over the side of the car 
to see the world stretching out far and wide below them at 
the depth of seven miles. Above them lay the open regions of 
space stretching away into all infinity. About them reigned 
a silence impressive and majestic, for no sound could come 
up through the thin air to tell of human activity so busy on 
the earth below, while the great empty depths of space 
could not carry sound from interstellar regions. Shut off 
in the lonely silence of the upper regions of the air, the 
weakness and insignificance of man must have been forcibly 
impressed upon them. To ascend to such great altitudes, 
however, is no pleasant feat. It is attended with danger 
to life and limb. Unpleasant sensations occur owing to the 
rarefaction and low pressure of the air. The elastic force of 
the gases of the tissues, having but a slight external opposing 
power, is apt to cause distension of the blood vessels and 



THE ELEMENT HYDROGEN 119 

bleeding of the nose. The respiration and circulation become 
quickened. Gay Lussac's pulse beat 120 to the minute, its 
normal rate being 66. Glashier fainted away and Coxwell's 
hands becoming numbed by the intense dreadful cold and 
lack of air prevailing in these high regions, he had to pull the 
cord controlling the escape valve with his teeth in order to 
descend to lower regions ! 

In an ascent made by Tissandier, Sevil, and Croce- 
Spinelli, the last two actually died in the balloon from 
want of air. These dangers are now somewhat obviated by 
carrying cylinders of compressed oxygen, which is cautiously 
respired when the supply of air fails. 

Hydrogen gas is, like air, colourless, tasteless, and odour- 
less. It burns with a feeble non-luminous flame, producing 
water : 

2H 2 + 2 2H a O 

Hydrogen Oxygen. Water. 

Nevertheless the gas when mixed with the proper amount 
of air or oxygen will explode most violently, producing water. 
This may be shown by means of a very striking experiment. 
A thin glass flask is filled with a mixture of hydrogen and 
oxygen in the ratio of 2 : 1, and the mixture is ignited by 
means of an electric spark. Instantly there occurs a flash 
of light and a deafening explosion, and the flask is shattered 
into a fine dust (Fig. 20). 

One pound of hydrogen in burning to water develops 
enough heat to raise 34,200 pounds of water one degree 
centigrade. This is an amount of heat so great that if 
directly converted into work it would hurl a ton weight into 
the air to the height of over two miles. 

To liquefy hydrogen gas it must be cooled below its 
critical temperature, which lies as low as — 241 ° C. The 
first to achieve this was Olszewski in 1884 ; but he 
only obtained hydrogen in a momentarily liquid state. 
Dewar was the first to obtain it in quantity, by its means 
giving us a glimpse of a strange cold world in which the 
temperatures prevailing are only a little above the absolute 
zero of temperature itself, and where matter is consequently 
in an almost heatiess state. In this strange region of science 



i 



120 MODERN CHEMISTRY 

all substances pass into a changeless dead condition ; they 
are, so to speak, chilled into an everlasting sleep so far as 
the chemical activities of their molecules are concerned. 
Bodies such as strong acids or bases, which are distinguished 
for their chemical activities at ordinary temperatures, become 
as inert as nitrogen or carbon at ordinary temperatures. 
The only substance which still retains to some extent its 
chemical activities under these conditions is fluorine. 

Matter in this intensely cold condition furnishes many 
interesting problems for experiment and speculation. It gives 
us a picture of the normal state to which the surface of a 
planet would attain in the depths of space, unless continu- 
ously warmed by a sun. Myriads of such cold planets must 
even now circle in silent darkness about burnt-out suns 
in the universe. Indeed every comet which rushes round 
our sun and then retreats into infinite space whence it 
came, experiences this degree of cold during the greater part 
of its journey. 

fc All these wonderful results were achieved by first com- 
pressing hydrogen gas to about two hundred atmospheres' 
pressure, cooling it in liquid air, and then letting it expand 
continuously through a long tube. As it expands its tem- 
perature is progressively lowered until at last it reaches a tem- 
perature of — 252. 6° C, at which low temperature hydrogen 
gas condenses to a liquid. What a wonderful liquid too, 
this is ! It is as clear and mobile as the clearest crystal 
water and yet so intensely cold as to burn like fire ! A drop 
on the arm freezes blood and skin to a hard mass and 
produces a wound like the touch of a red-hot iron. 
It is a wonderfully light liquid, — far lighter than any other 
liquid with which we are acquainted. It is fourteen 
times lighter than water, so light indeed, that cork, wood, 
and oil sink in it like lead in water ! By evaporating this 
liquid an even more intense cold is produced, and finally, 
if the evaporation is rapid enough, the cold liquid will freeze, 
and become a solid ice-like mass, which melts at — 258=9° C, 
only 14° from the absolute zero of temperature itself ! 
Recently by the same process Onnes has succeeded in lique- 
fying helium gas, which boils at only 4.5 absolute, and by 




THE ELEMENT HYDROGEN 



121 



evaporating this liquid matter has been cooled to within 3 C. 
of the absolute zero of temperature, the greatest degree of 
cold ever yet produced !* 




Fig. 20. — Explosion of a Flask filled with a mixture of Hydrogen and 
Oxygen Gases. When mixed together in the ratio of two volumes of 
hydrogen to one of oxygen the mixture will explode with a deafening 
report when an electric spark is passed through it. Unless the glass 
vessel containing the gases is very strong it will be shattered by the 
force of the explosion into dust. 

- All the properties of matter change at these low tem- 
peratures. Steel and copper become immensely stronger 
than they are at ordinary temperatures. Many dyes lose their 
colour ; crystals such as uranium nitrate become strongly 

* Onnes, Proc, K. Akad. Wetensch, Amsterdam, 1908, 10, 744 ; 
II, 168. 



122 MODERN CHEMISTRY 

electrified, shining like phosphorus in the dark and emitting 
electrical discharges. All life, motion and change, to which 
we are accustomed all our lives, and which is the product of 
molecular motion, becomes an impossibility. Matter chilled 
to such temperatures becomes as changeless as death itself. 

" Liquid hydrogen," says Dewar,* " introduces the 
investigator to a world of solid bodies. ... It may be safely 
predicted that by its means many obscure problems of phy- 
sics and chemistry will ultimately be solved, so that the 
liquefaction of the last of the old permanent gases is pregnant 
now with future consequences of great scientific moment. . ." 
Speaking of the liquefaction of helium, now an accomplished 
fact, but at that time still the object of strenuous endeavour, 
the distinguished Scotchman says : " The descent to a 
temperature within five degrees of the absolute zero would 
open out new vistas of scientific inquiry, which would add 
immensely to our knowledge of the properties of matter. 
To command in our laboratories a temperature which would 
be equivalent to that which a comet might reach at an infinite 
distance from the sun would indeed be a great triumph for 
science. . . . The chemists of the future will find ample 
scope for investigation within the apparently limited range 
of temperature which separates solid hydrogen from the zero. 
Indeed, great as is the sentimental interest attached to the 
liquefaction of these refractory gases, the importance of the 
achievement lies rather in the fact that it opens out new 
fields of research and enormously widens out the horizon of 
physical science, enabling the natural philosopher to study 
the properties and behaviour of matter under entirely novel 
conditions." 

As Dewar rightly remarks, even if the absolute zero of 
temperature were reached by the investigator, it is by no 
means certain that he would find the near approach of the 
death of matter sometimes pictured ; for even supposing 
that all the heat motion was removed from the molecules 
this would not affect the tremendous motions going on within 
the atoms themselves. The atoms would still remain 
microcosms full of stupendous electronic motions and change, 
* Address to the British Association, 1902. 



THE ELEMENT HYDROGEN 



123 



the very existence of which was, until the advent of radium, 
entirely unsuspected, except by a few advanced thinkers. 

We must now say a few words about the structure of hydro- 
gen gas. The gas, when contained in a glassvessel, appears 
to be perfectly transparent and structureless. But this is 
entirely due to the coarseness of our eyesight. Could we but 



(tF~ \\\ 




•ffe^ Ja7-^B§\ ■•-'■ 


' ^ 








^»mM jrajfl 


ft 11 

yr. * 




Vie-*' 





Fig. 21. — Imaginary Representation of the Structure of Hydrogen 
Gas. The gas consists of myriads of tiny molecules, each molecule 
consisting of two atoms revolving swiftly round each other. The 
molecules are at ordinary temperatures darting about with a speed 
of over a mile a second. 

inspect the hydrogen through a microscope which magnified 
a few million times a wonderful unseen universe would flash 
into view. The gas would resolve itself into a swarm of 
countless myriads of fine particles flying about in our field 
of view, something after the manner of motes in a sunbeam, 
only far more swiftly. These are the hydrogen molecules. 
They are so exceeding small that the volume occupied by 
the smallest particle of dust visible to the eye contains 



124 MODERN CHEMISTRY 

ample room to pack away a billion of them. In the gas as 
it occurs at ordinary atmospheric pressures the molecules 
are separated by distances which are many thousands of 
times their own diameters. They are, in reference to their 
diameters, as far apart in the gas as the solar system is 
distant from the nearest fixed star. If the whole structure 
of hydrogen gas was magnified ten thousand trillion times it 
would, as Fournier d'Albe pointed out, look very much like 
the stellar universe of which we form a part. A cubic foot 
of the gas when thus magnified would swell out into a vast 
universe as thickly peopled with atoms of stellar dimensions 
as the Milky Way is with stars. 

The hydrogen molecule consists of two atoms which accom- 
pany each other on their journey through space, the one 
atom probably revolving around the other, much as the 
earth revolves around the sun or the moon around the earth. 
When we inspect some of this invisible gas imprisoned within 
a glass vessel it is indeed difficult to realise that the whole 
consists of myriads of molecules travelling at the speed 
of over a mile a second — faster even than a rifle bullet ! 
Yet this is so; at o°C. their average velocity amounts to 
1,844 metres a second. Of course many of the molecules 
travel far faster and others far slower than this. The 
number given is the mere average of the different velocities. 

The real hydrogen atom is very small, but by no means 
indefinitely so. Chemists have estimated their actual 
diameter as 0.2 millionth of a millimetre (2 xio~~ 8 cm.). 
Their actual weight is about 1.4X10— 24 gram.* 

If we were to magnify a volume of hydrogen as large as a 
hazel nut up to the size of the earth we would see each 
hydrogen atom in it about the size of a golf ball. How 
would it look ? Probably absolutely unlike anything that 
we can imagine. All that we know about it is that it is not 
the simple structure that it was once thought to be. The 
chemists of the last generation were accustomed to think of 
it as a very small solid particle in shape something like our 
earth, or perhaps, of a simple geometrical shape, and com- 
posed of a simple material called " Hydrogen stuff " ; but 

* Meyer's " Kinetic Theory of Gases " (1899), p. 331. 



THE ELEMENT HYDROGEN 125 

recent discoveries have led to the conclusion that the atom 
itself is an extremely complicated structure, built up of 
about 2,000 smaller negatively-electrified particles, the elec- 
trons all revolving in complicated systems of circles about 
the centre of the atom, something after the manner of the 
planet Saturn and its rings of small asteroids.* 




Fig. 22. — Structure of the Hydrogen Atom according to the Modern 
Electronic Theory. A central positively charged mass has arranged 
round it in a series of concentric rings many hundreds of negatively 
charged particles called electrons. The particles composing the rings 
are supposed to be rapidly rotating about the central mass. The 
whole system thus resembles somewhat the planet Saturn and his 
rings. 

We thus see that the element hydrogen, usually regarded 
as such an uninteresting subject for study by one approach- 
ing it for the first time by means of one of the numerous 
elementary " cram " books of chemistry which cater for 
examinations that eat like a canker into our educa- 
tional system, is in reality no dry or uninteresting subject. 
Rightly viewed it teems with problems still unsolved which 
are capable of providing food for thought and work to occupy 
a whole lifetime. 

* See J. J. Thomson, Philosophical Magazine (6), Vol 7, p. 237 
(1904). Nargarka, Nature, Vol. 69, p. 392 (1904). 



CHAPTER VII 

THE AIR 

The mystery of the air has fascinated poets and thinkers 
for ages. That we live at the bottom of a vast ocean of 
some invisible medium has, of course, been known since the 
earliest times of which we have any record. Such a fact 
could not have escaped the most unthinking savage. He saw 
the power of this medium in the cyclones and tornadoes 
which hurl mighty trees into the air like so many straws, 
and which overwhelm whole forests in swift destruction. 
The terrible powers of this medium led primeval man to 
associate it with invisible beings, gods and devils, who 
haunted the sky and empty spaces, and when they were 
angry dealt out death and devastation. The swift rush of 
the wind was to him the rush of mighty spirits, the wailing 
and moaning of it among the trees was caused by the wailing 
of lost souls in distress. Land and sky were full of horror 
and mystery.* Even to-day, in popular superstitution, 
spirits are represented as transparent, unsubstantial visions 
that arrive in an ice-cold draught, and vanish again into 
thin air, ideas v/hich are the remnants of superstitions, 
thousands and thousands of years old, handed down in 
unbroken succession from time immemorial. What are 
the Greek gods, dwelling among the clouds, and revealing 
their powers in rain, hail, lightning, and thunder, but the 
remains of this air-worship ? The warlike and hardy 
natives of the cold and gloomy North also referred all natural 
phenomena to gods living in the air. Thus the mysterious 
Northern Lights, which flared so gloriously in their skies, 
together with lightning, thunder, and earthquake, were all 
attributed to supernatural agency : — 

* Even the highly-civilised Greeks worshipped the winds. 

126 



THE AIR 127 

M The light thou beholdest 
Stream through the heavens 
In flashes of crimson 
Is but my red beard 
Blown by the night wind 
Affrighting the nations ! 
Mine eyes are the lightning, 
The wheels of my chariot 
Roll in the thunder ; 
The blows of my hammer 
Ring in the earthquake." 

These are the words put into the mouth of the great war- 
god Thor in Elgar's version of the old Norse legend of King 
Olaf. In the analogous southern superstitution the roar 
of thunder is the rumble of the wheels of God's chariot 
rapidly driven across the sky, and the lightning is caused by 
the cracks thus produced in the floor of heaven, through 
which inconceivable glory and splendour bursts forth for 
an instant. 

Many among the untold millions of men who have passed 
away since human life, thought and civilisation began to 
flourish upon the earth must have pondered upon the 
mystery of the air ; yet during all this vast interval no one 
seems to have guessed its true nature until within a period 
so recent that it may be bridged over by the lives of two 
old men ! 

In very early times in Greece it was suspected that air is 
a thin, invisible form of matter having an atomic constitu- 
tion. Vitruvius distinctly states that air has weight. We 
read of Aristotle making experiments on the weight of air 
by weighing a bladder when empty and when blown out, 
but, on account of the conditions of the experiment, with 
necessarily negative results. Then for near two thousand 
years intellectual darkness settled upon the world. The 
spread of a metaphysical philosophy which despised experi- 
ment, combined with the throes caused by the birth 
of new religions, crushed for many hundreds of years all 
aspirations of science, all gropings for light. The whole 
mighty fabric of ancient civilisation and intellectual life 
was overwhelmed by the inrush of barbarian warriors, 



128 MODERN CHEMISTRY 

and the influence of the priests more than completed the 
ruin that the armies of Attila had begun. 

In the fifteenth and sixteenth centuries Science gradually 
lifted up her torch of learning again, and with her advance 
our knowledge of the constitution of the air has gradually 
increased to the present day. 

Air is matter. If possesses weight. Although invisible 
it is as truly material as a piece of stone or a brick. One 
cubic yard of air weighs about 2.2 lbs. A moderately sized 
lecture-hall will contain thirty to forty tons of it. If all 
the air in such a hall were frozen into one solid lump and 
dropped from the ceiling to the floor it would crush any one 
beneath into a formless pulp, and the thunder of the fall 
would be heard for many a hundred yards around. Think 
of the shock caused by the fall of a mass of thirty or forty 
tons of iron from such a height, and you will obtain a notion 
of the disturbance that would be caused by the fall of the 
equal mass of air contained in the room. The weight of the 
whole atmosphere amounts to 5,210 billion tons ; over each 
square yard of earth there lie between eight and nine tons 
of air. 

If air is really so substantial a thing, why cannot we see 
it ? Why is it invisible ? The reason is that we are im- 
mersed in it. It surrounds us on every side. We can see 
water, but the fish in the sea cannot see it because they are 
immersed in it. Yet we can see bubbles of air in water, 
just as we can see drops of water in air. The fact of the 
matter is that confines and boundaries are necessary to 
vision. A body, before it can become visible, must exhibit 
some contrast of colour and transparency, some difference 
of light and shade, compared with surrounding objects before 
the eye can seize on these indications and the brain swiftly 
interpret them as due to the presence of a body. We never 
see a body. We only see, strictly speaking, differences of 
light and shade and colour from which, by a purely mental 
operation, we infer its form and attributes. The air presents 
to our eyes (if we except hot air ascending through cold air) 
none of these necessary indications of its presence, and so 
goes without perception, 



THE AIR 129 

In the same way, though we live immersed in and sur- 
rounded on all sides by a medium, the mysterious ether, which 
is thousands of times denser than granite and millions of times 
stronger than steel,* yet we are totally unaware of its 
presence, and we only infer its existence on the evidence of 
highly elaborate physical experiments. 

Under this great ocean of mobile gas which we call the 
atmosphere, and for the most part by its agency, take 
place all the ceaseless changes and eternal circulation of 
matter which is going on so rapidly all over the earth's 
surface. In the absence of such a layer of gas the world 
would be a barren, changeless waste. Indeed, the atmosphere 
is at once the cradle and mother of all that is beautiful, of 
all that lives and moves upon the surface of this fair green 
world of ours. Though its commotions sometimes terrify 
us by their violence and bring death and destruction in their 
train, yet, as a whole, it deals gently with us. Few realise, 
for example, how well it protects us from the awful cold of 
space. Outside the world a temperature of nearly -273°C. 
prevails ; and yet even in the coldest and darkest of 
Arctic nights, when the sun ceases to warm the surface 
of the earth for months at a time, the temperature never 
falls to more than a few scores of degrees below the 
melting point of ice ; still in the hours of a single night 
there is ample time for the rocks and soil to radiate 
away nearly all their heat and sink to such a state of 
cold as would speedily bring all animal life upon the world 
to a close. 

Why, then, does this not happen ? The reason is that the 
atmosphere, like a warm blanket, encircles the earth and pre- 
serves us from this death-bringing frost. The atmosphere, 
in fact, possesses the same properties as a glass hot-house. 
It allows luminous rays of light and heat from the sun to 
reach the earth and warm its surface, but it will not allow 
dark heat rays, such as come from a kettle of boiling water, 
or a mass of sun-warmed earth, to escape again into space. 
It therefore stores up the heat of the sun and protects the 
Surface of the earth from the evil of a too. rapid cooling, in 
* Sir Oliver Lodge, " The Ether of Space," 1909. 



130 MODERN CHEMISTRY 

much the same way that an overcoat keeps our bodies 
warm on a winter's day. 

The atmosphere also protects us from the awful artillery 
of heaven. The swiftest of our bullets fly through the air 
with a velocity of less than half-a-mile a second ; yet in 
the empty depths of space rush countless myriads of iron 
meteorites — ranging in size from that of a microscopic grain 
of dust to that of a great mountain — flying silently through 
the frictionless ether with the stupendous velocity of from 
twenty to a hundred miles a second. If our atmosphere 
ceased to shield us they would rain down night and day 
upon the earth, striking its surface with terrific force, 
shattering the stoutest structures, and plunging for hundreds 
of feet through the hardest rocks. When we consider that 
a projectile from a modern twelve-inch gun, flying with a 
velocity of about a third of a mile a second, will crash through a 
foot of hardened steel as through a piece of paste-board, we 
can form some idea of the smashing force of these heavenly 
projectiles which, travelling hundreds of times faster, 
possess, weight for weight, an energy hundreds of thousands 
of times greater than any earthly missile. Strange as it may 
appear, however, at first, it is their very speed which preserves 
us from them ; for, plunging into the atmosphere with such 
velocities, they encounter a terrific resistance. The friction 
causes them to become white-hot, and they burn away or 
shatter into a fine dust long before they reach us. The 
sudden blaze into splendour and the slow-movir-? trail of 
glory which marks the passage of a meteor across the sky 
announces at the same time the end of one of these heavenly 
projectiles. 

Meteors have been observed to inflame at a height o£ioo- 
125 miles. Consequently quite an appreciable amouj*i«of air 
must exist even at these high altitudes. Arrhenius estimates 
the average height of the atmosphere as 250 miles, and some 
authorities extend it to over 500 miles. However this 
may be, the quantity of air and consequently its pressure, 
rapidly diminishes as we ascend the atmosphere. 

Thus at a height of merely 4,296 metres (at Potasi) the 
pressure is only 0.62 that of the air at the sea-level. Glaishier 



THE AIR 131 

found in his balloon ascents that at a height of between 
six and seven miles the atmospheric pressure had sunk 
one quarter of its value at the sea-level. At fifty km. (31 
miles) the pressure is only 0.3 mm. compared with 760 mm. 
at the sea-level, while at the height of 100 km. (62 miles) 
the pressure sinks to 0.02 mm. No further away than sixty 
miles above us, then, there reigns a vacuum as perfect as 
that producible by many air-pumps. A man suddenly 
ascending to such heights would die in convulsions. The 
instantaneous release of the pressure that our bodies supports 
(15 pounds on the square inch, 14 tons over the whole adult 
body) might cause internal blood vessels to give way and 
blood would come pouring through the ruptured walls into 
the brain, nose, eyes, and ears ; and yet, for hundreds of 
miles above this, the atmosphere still exists. " Above us," 
says Trowbridge,* " there extends a vast unexplored space 
far more interesting from a scientific point of view than the 
icy regions around the North Pole. No one can ever reach 
the limit of the upper regions of the air and live, unless he 
carries with him air to breathe and fuel to warm him ; for 
at the paltry distance of ten miles above the earth the ait 
is too thin to support respiration, and the thermometer would 
register far below zero. It would be a region of perpetual 
snow on a peak of the earth if it should rise to such a height. 
A person in a balloon would not hear a friend in a neigh- 
bouring Walloon, even if they were near enough to shake 
hands. J'here would be no medium for the propagation of 
sound waves." 

Yet these upper regions are neither structureless nor 
motionless. Every part of this space is in a state of intense 
and complex circulatory movement. In them mighty winds 
rush perpetually with a speed of seventy miles and more an 
hour. The atmosphere has been compared to a vast machine 
kept in motion by the heat of the sun's rays. The whole of 
it has been moving ihus for countless ages, and the different 
air-currents continually rushing through it form a vast 
mechanism of enormous complexity, the thorough explora- 
tion of which will occupy man for centuries to come. The 
* The Forum, (1898), Vol. 26, p. 561. 



I 



132 MODERN CHEMISTRY 

mystery and wonder of the regions of the upper air is increased 
by the fact, brought to light by modern researches, that it 
is the seat of great electric currents, which, according to 
Trowbridge, sweep around the whole earth. It is certain 
that the rarefied air of these high regions conducts electricity 
almost as well as the best metallic conductors. It is equally 
certain that the sun has been for countless ages blowing a 
stream of negatively charged particles into the upper 
atmospheric regions. These are deflected in a series of 
electric currents towards the magnetic poles of the earth and, 
arriving in northern regions, crowd together and give rise 
to those wonderful natural electrical displays known as the 
Aurora Borealis, whose flashes and streamers of violet, 
green, and crimson light were long ago likened to " burning 
spears," and gave rise to the notion that 

" Fierce fiery warriors fight upon the clouds, 
In ranks and squadrons and right form of war." 

The origin of the enormous volumes of gas which form our 
atmosphere has been for centuries a matter of active discus- 
sion among the learned. It is now believed that the atmo- 
sphere is nothing more nor less than the remains of that 
primeval fiery nebula from which the earth, sun, and solar 
system were evolved. Originally the whole was in a gaseous 
state, but in time the temperature of that part of the nebula 
from which our world condensed fell to such an extent that 
the more involatile heavy constituents were deposited in its 
central regions in a liquid state, and in time became covered 
over with a solid crust, thus forming the body of the earth. 
The more volatile gases and vapours remained behind, how- 
ever, and the atmophere is merely those portions of the 
nebula which the present temperature of the earth's surface 
is sufficient to maintain in a gaseous state. Thus we see 
that the process of condensation of the nebula is by no means 
completed. In future ages, as the temperature of the earth 
slowly sinks, the gaseous air will be deposited first in a liquid 
and finally in a solid form, and it is only when this final stage 
of evolution is reached that we can regard the fiery earth- 
nebula as completely condensed. 

It is a curious thought that the very wind which rushes in 



THE AIR 133 

our faces as we walk along the streets possesses an antiquity 
before which the oldest hills, and even the oceans, are 
things of yesterday. This wind began to blow at a time when 
the earth was " without form and void," a mere expanse of 
gas, and ever since that distant time it has never ceased 
to move ; and for countless ages to come, day in, day out, it 
will continue to rush until it sees the sun decline from bright 
yellow to dull red, and finally sink amidst the gloom of the 
blackest night into darkness. Then, and not till then, will 
the atmosphere cease from its long race of ages and condense 
into solid matter like the rocks around us. 

Air is a mixture of various gases. By far the greater 
part of its bulk consists of the two gases, nitrogen and oxy- 
gen, in the proportion of about four to one respectively. 
The active constituent of the air is the oxygen which allows 
bodies to burn. The nitrogen is a dead, inactive substance 
which will not support combustion or respiration. The 
proportions of the other gases air contains is small. We 
give here a table of its constituents taken from the most 
recent and accurate modern researches : — 

TABLE. 

One cubic metre* (100 litres) of dry air consists of 

780.3 litres of Nitrogen gas weighing 975.80 grams. 

209.9 „ „ Oxygen „ „ 299.84 „ 

9.4 „ „ Argon „ „ 16.76 „ 

0.3 „ „ Carbon dioxide „ 0.59 „ 

0.1 „ „ Hydrogen „ „ 0.01 



1000 litres 1293.00 grams. 

Besides this there occur the following traces of rare inac- 
tive gases which have been recently discovered : — 

0.015 litres Neon weighing 0.01339 grams. 

0.0015 „ Helium „ 0.00027 „ 

0.0015 „ Krypton „ 0.00018 „ 

0.0000006 „ Xenon „ 0.00003 ,, 

* One metre = 39.371 inches. 1 lb. = 454 grams. 



134 MODERN CHEMISTRY 

There also exist small traces of ozone, ammonium nitrite, 
and nitrate, sulphuretted hydrogen, micro-organisms, dust, 
etc., etc. 

An illustration suggested by Graham will make these 
proportions clearer. 

He imagines the air to be suddenly divided by magic into 
its components, arranged in non-mixing layers in the order 
of their specific gravities. Then we would have resting upon 
the surface of the earth the following layers, one upon 
the other : — 

Water (liquid) . . . . 5 inches. 



Carbon dioxide . . 


. . 13 feet. 


Argon 
Oxygen 

Nitrogen . . 


. . 90 yards 
1 mile 
4 miles. 



Of course, this would be on the assumption that these gases 
were compressed so as to be under normal atmospheric 
pressure throughout. 

The amount of water spread through the air in the form 
of an invisible vapour varies pretty widely. One hundred 
volumes of air contain on an average 1.3 volumes of aqueous 
vapour. This forms only 0.84% of the weight of the air. 
A cubic metre of air contains about ten grams of water 
vapour — a small amount, you will say, at first sight. Yet if 
we consider the whole immense bulk of the atmosphere the 
amount of water thus held in it in the invisible form of vapour 
is enormous. It amounts to nearly fifty billion tons ! 
This is enough water to form a lake one mile deep and 
covering 12,000 square miles of land ! 

This invisible gaseous water exerts an enormous influence 
upon the climate of our world. If it were all removed the 
average temperature of the atmosphere would fall by nearly 
20° C, and consequently the greater part of the earth's 
surface would be converted into a vast ice- waste such as 
prevails within the Arctic circle ! The reason is that water 
vapour is transparent to luminous radiations from the sun, 
but opaque to non-luminous. It will let the sun's rays reach 
the earth and warm it, but it will not let the dark heat rays 
which then begin to be emitted by the warm earth to escape 



THE AIR 



135 



into space. They are nearly all caught by the aqueous 
vapour and carbon dioxide in the atmosphere, which thus 
keeps up the general temperature all over the earth's surface. 



60 MILES 



30 MILES 



LIMIT OP 
CLOUDS 

HIGHEST MOUNTS 
6 MILES 

SEA LEVEL 



HYDBOGEN. HELIUM 



HYDROGEN, fiELIUH 
QZQHE, NITROGEN 



LAYEK OF AIR RICH IN 
OZONE, OXYGEN, NITROGEN 



OXYGEN. NITROGCH CARBON DlOMEE 

, W\TE£ VAPOUR, 




Fig. 23. — A Section through the Earth's Atmosphere, showing how its 
composition alters as it goes upwards. 

Water vapour is much lighter than air. It weighs only 
0.62 times that of an equal volume of dry air. It is conse- 
quently about as light as the coal gas used for filling balloons. 
This lightness causes the vapour-laden air to rise upwards 
into the cold upper regions of the atmosphere, and there the 
vapour condenses to tiny drops of visible water, which form 



, 



136 MODERN CHEMISTRY 

the white clouds which float in the sky. This is the reason 
why clouds usually occur far above the surface of the earth. 
Notice now how the apparently most insignificant scientific 
fact is fraught with world-wide consequences. For example, 
if water vapour had happened to be heavier than dry air, 
the moist air would never leave the earth's surface at all, and 
what an immense difference this would make in our lives ! 
Our eyes would never behold bright gleaming sunlight and 
blue summer skies. We should live for ever in a fog denser 
than any London fog. We should be enshrouded in a pall 
of white mist heaped up thousands of feet above us, which 
would shut off from our eyes all the beauty of rolling lands- 
scape, all the grandeur of hill and dale. Under such condi- 
tions we could have had no Turner, no Constable, no David 
Cox, nor De Wint. Everywhere gloom, dampness, and 
monotony would prevail. Although we could hear from 
afar the thunder of the Niagara Falls or the roaring of the 
waves upon the sea-shore, our eyes could by no possibility 
penetrate the dense rolling fog which hid these majestic 
sights from us. We might possibly be ignorant of their 
very cause ! The great waters of the earth, covered as they 
would be with vast masses of impenetrable fog, would 
remain gloomy and unknown regions, full of mystery and 
horror. Indeed it is doubtful whether, under such circum- 
stances, man would ever have developed into a civilised being 
at all. 

The amount of carbon dioxide in the air, though small 
(0.03 per cent.), is of great importance, since from this 
substance is obtained all the carbon of animal and vegetable 
life. The amount of it varies considerably as regards 
locality, being greater over great towns than in the 
country, and greater in the country than over the sea. It 
appears to be somewhat more abundant at a certain 
distance above the earth (0.033 P er cent.) than on the 
earth's surface (0.029 P er cent.). The reason of this is 
that volcanoes and tall chimneys are continually sending 
up vast currents of the gas high into the air, while plants are 
feeding on it and continually withdrawing it from the lower 
regions of the air. The people of the earth evolve in their 



THE AIR 137 

breath about one and a half million tons of this gas daily, 
but far greater quantities than this are produced from other 
sources, such as the decay of vegetable and animal matter, 
from fires, volcanoes, and earth fissures. There will be more 
to say about these matters when we come to deal with this 
gas in a later chapter. 

The small amount of ozone in the air also varies widely. 
Near the earth's surface, especially near the air of towns, 
it seems to disappear entirely ; but as we ascend the atmos- 
phere the amount rapidly increases. On the top of high 
mountains the amount has risen to four times the amount 
found in lower regions. Doubtless at still higher levels, 
where great cold and low pressure favour its production, 
and where great currents of electricity stream and the action 
of the ozone-producing ultra-violet light of the sun is at a 
maximum, the proportion of ozone must be much greater. 
Indeed it has been suggested that the greater part of the 
oxygen of the air is in these regions converted into ozone, 
and that the tiny traces of this gas which exist in lower 
regions must have filtered down from above. 

The lightest gases of the atmosphere, which are continually 
exuding out of the earth into the air, naturally ascend slowly 
but surely to the highest regions. And thus it comes about 
that at the height of 100 km. (62 miles) the atmosphere con- 
sists entirely of hydrogen (99 J per cent.) and helium \ percent.* 
We know this, not only from theoretical considerations, but 
also from observed facts. For example, when meteors flash 
into visibility at the height of a hundred miles the spectrum 
of the light they send out show that they are rushing through 
an atmosphere of hydrogen and helium. 

Consequently if a mountain projected to this height into 
the air, and supposing that the difficulty of the rarefaction 
of the air at such an altitude was overcome, it would still 
be quite impossible for any animal to live even for a minute 
in the air at the summit. For here there would exist no free 
oxygen for the animal to breathe, and it would die of suffoca- 
tion. In air of this composition, even if highly compressed, 

* Erdmann, " Lehrbuch der Anorganischen Chemie," pp. 347 
(1906). Dewar, " Address to the British Association," (1902), p. 20. 



138 MODERN CHEMISTRY 

a candle would not burn, and coal and paper would be as 
incombustible as brick or stone ! 

It is very remarkable, however, that a heavy rare gas, 
krypton by name, should be observed to send forth light 
at the height of over a hundred miles, as is shown by an 
examination of the spectrum of the Aurora Borealis. 

For the gas has an atom 81.2 times heavier than that of 
hydrogen, and so would not be expected to accumulate in 
such high regions. 

The upper expanses of the air thus present many mysterious 
problems for solution, and we are only just beginning to 
learn something of its hitherto unsuspected wonders. 

The air appears under ordinary circumstances quite invis- 
ible and structureless. But a single beam of bright sunlight 
streaming through a crack into a dark room teaches us other- 
wise. We see that the air is filled with a countless multitude 
of tiny dust particles in ceaseless motion. Over each great 
town this dust lies like a veritable sea ; but it is present, 
though in greatly diminished quantity, at the greatest 
heights to which the atmosphere ascends. Whence comes 
it ? Near the earth's surface it is the finely-powdered soil, 
grains of sand from the sea-shore, and salt from the sea- 
spray, mingled with the tiny bodies of myriads of useful 
and deadly bacteria, all swept upwards by wind and air 
currents, and kept suspended in the atmosphere by reason 
of their extreme minuteness. 

In the highest regions of the atmosphere the explanation 
is otherwise. The dust there, descending in a steady stream 
age after age upon the world's surface miles below, comes 
from without the limits of the atmosphere. It is cosmic 
dust. For every star in this great universe of ours, every 
sun, and almost every planet, visible and invisible, is blowing 
ceaselessly into space a stream of tiny dust particles. With 
every volcanic explosion that takes place upon this earth 
a cloud of volcanic dust ascends to heaven, and some of it 
is hurled right away into space. On the sun, and on the 
millions of similar bodies which shine in the sky at night, 
hundreds of such explosions, vaster far than the mightiest 
dynamite explosion ever produced upon this earth, take 



THE AIR 139 

place each second all over their surfaces ; and with each 
of these there fly off into space hundreds of tons of this dust. 
It has been estimated that the sun in each year loses in this 
way three hundred thousand million tons of dust, and the 
earth gains in the same time interval no less than twenty 
thousand tons of it. 

Since this has been going on for eternities of time through- 
out all space, the whole universe, as far as the greatest tele- 
scopes can plunge into its vast abysses, is full of this dust. 
Indeed it is possible that most of the matter now bunched 
together in great globes like our sun or earth has once circu- 
lated through space as a fine dust, and will, in the course of 
time, so circulate again, not once but many times. The reason 
why the suns do not all evaporate away into such dust is 
because they receive in each instant as much as they throw 
out. The universe has in this respect attained equilibrium. 
This dust, once clear of sun or star, is often driven right 
away from it by the radiation pressure of light. It is thus 
streaming through space often with velocities of thousands 
of miles a second. Ultimately, these dust streams aggregate 
to form meteorites (and at a later stage comets, nebulae, suns 
and planets). Each meteorite which comes rushing into 
our atmosphere is again resolved by the immense factional 
heat into its primeval dust, which then again falls upon the 
earth. 

Most of this dust is electrified. It carries negative elec- 
tricity to us from the sun and causes those wonderful elec- 
trical discharges which astonish the dwellers in the Arctic 
and Antarctic regions. All the electricity circulating in 
our atmosphere, rushing in every flash of lightning, or 
eddying in every slow-moving fire ball, comes from afar, 
from the sun millions of miles away, and in part from stars 
in regions so remote as to be for ever invisible to human 
perception. 

This dust is of enormous importance to us. On it, and by 
its means, the invisible water vapour in the air condenses 
to clouds and rain. If the air were absolutely dust-free 
probably the whole of the land would be a rainless and 
waterless desert ; for it has been proved that without a 



140 MODERN CHEMISTRY 

nucleus of some sort aqueous vapour will not condense at all 
to visible drops. 

When we watch the countless motions of these little dust 
particles the mind suddenly realises that the air is far more 
complex than we had previously thought. It was this dust 
that suggested the atomic theory to the thinkers of old in 
India and Greece. The Indian philosophers imagined that 
we should merely have to divide each dust particle into six 
parts in order to reach the atoms. We know now, however, 
that the divisions must be carried out perhaps hundreds of 
faillions of times before this result would be reached. In 
met, if we could magnify the air a hundred million times, 
and thus bring its actual molecules into the bounds of 
visibility, its complexity would appear almost inconceivable. 
Each dust particle would swell into a vast galaxy of hundreds 
of millions of closely packed atoms about the size of walnuts, 
all bunched together and each in swift and incessant move- 
ment. Around it and colliding with it in all directions 
would stream countless millions of air molecules rushing 
with an average speed of 485 metres a second. Nor would 
the air molecules be all alike. If we could, like Alice in 
Wonderland, take up our standpoint on one particular mole- 
cule and watch the others stream past, we would see that 
out of every ten thousand molecules which swept by no less 
than 7,800 were nitrogen, 2,100 oxygen, 94 argon, 3 carbon 
dioxide, and only one hydrogen. The other gases are present 
in such a small quantity that if we imagined the air mole- 
cules to pass at the rate of one a second, we should have to 
watch night and day for nearly five years before we obtained 
a glimpse of a xenon molecule, and eight months before a 
krypton molecule came in sight. Three months would suffice 
for a helium molecule, and a week for a neon molecule to 
come past. Yet in a single minute no less than 48 nitrogen 
and twelve oxygen molecules would have passed. We may 
obtain some dim idea of what would be seen under suet 
conditions by looking at the whirling snowflakes falling 
incessantly downwards in countless numbers in a heavy 
snowstorm. Only we should have to imagine each snow- 
flake to be travelling about 500 yards a second in order to 



THE AIR 141 

make them conform to the velocities of the air molecules. 
They would thus drive past like bullets, or rapidly-moving 
hailstones. 

Now think that in one cubic centimetre of air, that is to 
say half a thimbleful, there are no less than sixty trillion 
molecules. Imagine then how many exist in our whole 
atmosphere which extends for miles in every direction ! 
The number is incomprehensibly vast ! Think now, of the 
mighty air currents flowing in different directions, of the 
great winds and storms. The winds are but mighty torrents 
of untold myriads of molecules flowing all in one direction. 
To an insect so small as to be capable of inhabiting a single 
air molecule in the same way that we inhabit the earth, the 
myriads of molecules sweeping past and onwards in the wind, 
in countless and endless numbers, would present much 
the same appearance, though far more numerous, that 
the streams of stars in the Milky Way present to the 
Earth's astronomers. What is the obj ect, what the end of this 
appalling complexity ? For each of these countless mole- 
cules has an individuality and a life of its own. Each speeds 
J on its way governed by forces with as much precision and 
" exactitude as the planets which swing in their orbits round 
the sun. 

Our grandfathers would have been much astonished if 
; they had been told in early youth that they would live 
[ to see the invisible air in which they lived reduced to 
" a clear sparkling liquid which boils on ice, freezes pure 
! alcohol, and burns steel like tissue paper ! They would 
1 perhaps have been even more astonished if they had been 
, told that in their time men would even succeed in freezing the 
[ air, in turning it into a white solid ice-like mass, so intensely 
I cold that its touch burns like the fiercest fire ! We propose 
1 to lay before the reader a brief account of the magnificent 
* modern researches which have led to these wonderful results. 
" To produce liquid air in the laboratory," says Dewar, 
" is a feat analogous to the production of liquid water starting 
f from steam at a white heat, and working with all the imple- 
ments and surroundings at the same high temperature. The 
' problem is not so much how to produce intense cold as to 



142 MODERN CHEMISTRY 

save it when produced from being immediately levelled up 
by the relatively superheated surroundings." After a 
century of continual effort human perseverance and endeav- 
our have at last succeeded in overcoming these difficulties 
with the result that liquid air may now not only be produced in 
gallons at a time, but it may be kept for weeks in wonderful heat 
impervious vessels first introduced into general use by Dewar. 
The principles involved in the liquefaction of air are simple 
enough. When a gas is compressed heat is evolved. Con- 
versely, when it is made to expand freely and suddenly cold 
is produced. The lower the initial temperature of the gas 
the greater is the cooling effect produced by its expansion. 
Linde, Hampson and Tripler have all constructed machines 
for liquefying air based upon these principles. A diagram, 
that of Linde's machine, is given in Fig. 25. Through a 
strong tube ABCD air enters at ordinary temperatures but 
under the great pressure of 200 atmospheres. By suitably 
regulating the throttle valve R the compressed air is allowed 
to expand suddenly at C into the chamber NO, where the 
pressure is only twenty atmospheres. A great cooling effect 
is thus produced, and the air thus chilled passes back up the 
tube EFGK, and thus cools further the incoming air in the 
pipe ABCD. This chilled air of the inner tube then expands 
as before at C, with a still further lowering of temperature, 
and the still colder expanded air thus produced continues to 
pass up the outer tube and chill more and more the incoming 
air until at last its temperature is lowered to such a point 
that the sudden expansion at C liquefies it to a colourless 
fluid which rapidly collects in the chamber NO. The cold 
air escaping through the outer tube EFGK passes again into 
pumps where it is compressed again to 200 atmospheres, 
cooled by water coolers to ordinary temperatures (for it is 
strongly heated by the compression) and again allowed to 
enter through the inner tube. Seeing that an extremely 
low temperature prevails in all these tubes they must be most 
carefully preserved from external heat by packing in non- 
conducting wool or feathers. Also in the actual machines 
the parts of the tubes shown in the diagram between B and 
E are hundreds of yards long, and, in order to save space, 






THE AIR 



243 



are coiled spirally. The commercial separation of liquid 
air into its constituent gases, oxygen and nitrogen, will be 
dealt with under the heading, " Manufacture of Oxygen Gas." 
The problem of keeping this liquid air when obtained was 
a very serious one. It is similar to the problem of keeping 




Air Combrcsscd 

VV i — 



]ssOin£Air at 
ZQ atmos|pheve» 




Fig. 25. — Linde's Apparatus for Liquefying Air. 

water from boiling away when surrounded on all sides by a 
white hot furnace. Dewar solved the difficulty by placing 
it in a doubly walled vessel, the space between whose walls 
had been previously carefully evacuated. The empty space 
forms an almost perfect insulation and in such vessels liquid 
air may be kept for weeks at a time. It may even be trans- 
ported in such vessels for thousands of miles with but little 



144 MODERN CHEMISTRY 

loss, although surrounding the liquid air on all sides is a 
medium almost red hot in comparison to it. Think, too, of 
the curious possibilities that the invention of these heat 
impervious " Dewar Flasks " opens out. Centuries hence, 
when the world's supply of coal is almost exhausted, and 
firing has become immensely dearer, such vacuum-jacketed 
vessels may come into general use for keeping liquids hot 
or cold, and even for making the walls of houses imper- 
vious to heat or cold. Instead of making hot tea several 
times a day, the family may in future times make it, perhaps, 
once or twice a month, and store the hot fluid in one of these 
vessels and serve it out boiling hot from day to day as 
required ! 

Liquid air is nearly as heavy as water and quite as clear 
and limpid. When seen in the open air it is always muffled 
in a dense white mist that wells up over the edge of the vessel 
in which it stands, and rolls along the floor in beautiful 
billowy clouds. It presents, in fact, much the same appear- 
ance as a mass of boiling steaming water. The intense cold 
of the liquid causes the moisture in the surrounding air to 
condense as clouds, and it is this which gives rise to the curious 
phenomenon. 

No other substance in the world, excepting liquid hydrogen 
and liquid helium, is as cold as liquid air ; and yet the hand 
may be dipped into it fearlessly ! The sensation is only that 
of a soft cushion about the hand. Such it really is. The 
hand is so hot in respect to liquid air that a layer of vapour 
surrounds it and prevents the liquid from coming into actual 
contact with the flesh. However the hand must not be 
allowed to remain in the liquid for more than an instant, for 
if the liquid were actually to touch the flesh a severe injury 
like a burn would result which sometimes takes months to 
heal. Even a few drops retained on a man's hand will sear 
like a white-hot iron. For this reason liquid air has been 
used in surgical cases where cauterisation is necessary. It 
is stated to eat out diseased flesh quickly and rapidly. Indeed 
a well-known New York physician seared out a cancer by its 
means and entirely cured a difficult case. The early hopes 
entertained of its use in this direction do not, however, seem 



THE AIR 



145 



to have been realised. It is curious to note that over 200 
years ago, the burning effect of great cold revealed itself 
clearly to Milton's poetic imagination. In his " Paradise 
Lost " he thus grandly describes the Land of Absolute Zero : 

" A frozen continent 
Lies dark and wild, set with perpetual storms 
Of whirlwind, and dire hail which on firm land 
Thaws not ; but gathers heap, and ruins seem 
Of ancient pile : all else deep snow and ice. 

The parching air 

Burns frore, and cold performs the effect of fire." 

The grandest poetic and scientific imaginations are closely 
akin, and consequently, whatever science may unveil, the 

chances are that 
in the world's best 
poetry will be 
found hints of 
every discovery. 
-■ The intense cold 
of this strange 
fluid may be illus- 
trated by a num- 
ber of remarkable 
experiments. Thus 
melting ice, cold 
as it seems to us, 
is actually 180 C. 
above the temper- 
ature of liquid 
air. It is conse- 
quently as hot in 
respect to it as 
fat frying in a 




Fig. 26. — Vacuum Jacketed Vessel for holding 
Liquid Air. In these heat impervious flasks 
liquids may be kept hot or cold for days at a 
time. 



saucepan is in respect to our bodies, or as molten lead 
is hot in respect to boiling water. If therefore liquid 
air be poured upon ice it will fly off hissing like water 
from red hot iron. If some liquid air be placed in a metal 
tea-kettle and then set upon a block of ice, the air at once 
begins to boil violently, and a white vapour as of steam 



t 4 6 MODERN CHEMISTRY 

rushes from the spout and lid. If the kettle be placed over 
a fire of burning coals the heat of the fire causes the liquid to 
evaporate more rapidly and a stream of vapour shoots out 
of the spout to a great height. It looks like steam from 
a kettle of boiling water. If water be placed in the kettle 
as soon as the air has boiled away, it may be taken out as ice, 
while at the same time the bottom of the kettle will be found 
coated with solid carbonic acid and ice, frozen from the fire ! 
And all this happens with the fire glowing only an inch or so 
below ! It is very surprising, too, to see one's breath, blown 
into an open can of liquid air, sent back instantly with its 
moisture congealed into a miniature snowstorm. Even a jet 
of scalding steam is instantly frozen, for between steam and 
liquid air lies an abrupt temperature drop of nearly 300 C. 
Mercury is instantly frozen into a solid shining metal like 
silver ! This solid metal is as hard as granite, and can be 
cast into swords and tools. Thus, if a little paste-board 
box be made in the shape of a hammer head and filled with 
mercury, and, after suspending in it a wooden rod to serve 
as a handle, if the whole be immersed in liquid air, in a few 
minutes the mercury will be frozen so solid as to form a 
veritable hammer which can be used for driving nails into 
hard wood ! 

Such experiments as these bring forcibly before the mind 
the abyss of cold which reigns in space about us. By con- 
templating the intense coldness of liquid air — itself a hot 
body in comparison to the cold of space — we are enabled to 
realise clearly how exceedingly hot the world's surface would 
appear to a being dwelling in the cold and darkness of the 
waste regions of the universe. Such a being landing on the 
surface of our planet would be shrivelled up like a piece of 
meat in an oven. If he managed to escape in time back 
to his cold gloomy abode, he would doubtless, like Mr. Wal- 
lace, sit down and write a book proving conclusively that no 
living beings could possibly exist on such a scorching world 
as the earth ! 

We must remember, too, that the earth's surface, like 
every other hot body, is radiating away heat and light into 
space, only our eyes are not sensitive to perceive it. In 




Fig. 27. — Pouring liquid 
air out by the quart. 
When liquid air is thus 
poured out the in- 
tensely cold vapour 
causes all the moisture 
in the surrounding air 
to condense, and form 
billowy clouds, which 
roll along the floor in 
the manner shown in 
the illustration. 



Fig. 28. — Kettle of liquid air 
boiling on a cake of ice. 
The ice is 180 hotter than 
the liquid air in the kettle, 
which is soon covered with 
frost. 




Face page 140. 



THE AIR 147 

Le Bon's words : — " Down to the absolute zero of temperature 
all bodies incessantly radiate waves of light invisible to our 
eyes, but probably perceptible by the animals called noc- 
turnal and capable of finding their way in the dark. To 
them, the body of a living being, whose temperature is about 
37 C, ought to be surrounded by a luminous halo, which 
the want of sensitiveness of our eyes alone prevents our 
discerning. There do not exist in nature, in reality, any 
dark bodies, but only imperfect eyes. All bodies whatever 
are a constant source of visible or invisible radiations, which, 
whether of one kind or the other, are always radiations of 
light."* 

Air is liquid at— 180 C, and as we have seen, if we raise its 
temperature above this, it will boil just as water does when 
heated above ioo° C. Steam, in fact, bears the same 
relation to water that ordinary air bears to liquid air. Since 
the earth's surface is nearly 200 C. above the temperature 
at which liquid air boils, it acts in the same way towards 
this fluid as a coal fire acts towards water. Hence we 
have only to expose liquid air to the heat of the furnace about 
us and in which we live, and it boils instantly, producing, like 
water surrounded by a fire, a vapour which expands and 
produces power. We can therefore use liquid air as a motive 
power. 

The pressure exerted by liquid air in regaining its gaseous 
state is simply enormous. Hardly any closed vessel could 
withstand it. This becomes easily intelligible when we 
consider that a single cubic foot of liquid air contains 
condensed within it about 750 cubic feet of air at 
ordinary pressures and temperatures. If therefore it 
be left to absorb heat from the surrounding air it will 
expand by this amount, and, if prevented from so doing 

i by being confined in a closed vessel, it will exert a 
pressure at ordinary temperature of over 10,000 lbs. (four 
and a half tons) on the square inch ! If heated the pressure 

, would amount to from ten to thirty and more tons on 
the square inch. No ordinary boiler could resist such 
gigantic pressures. Yet one can realise easily that if this 
* Le Bon, " The Evolution of Forces," p. 318 (1908). 



148 MODERN CHEMISTRY 

force could be confined and controlled it would give rise to 
an immense amount of power. It has indeed been suggested 
that liquid air could be used for driving high-speed engines 
for flying machines and other purposes where great power 
combined with lightness is essential. The great obstacle 
to its use, however, is the freezing effect it produces. The 
moisture of the air is rapidly deposited as ice upon the 
machine, especially round the orifice from which the jet 
of extremely cold air emerges. This soon closes the exit- 
tube and stops the machine. There are other disadvantages 
too, which cannot be discussed here. The expansive power 
of liquid air may be demonstrated easily by pouring a little 
into a tightly plugged steel barrel. In a short time the plug 
will be expelled with a loud detonation, and sent whirling 
for hundreds of feet into the air. Some liquid air poured 
into stout steel or copper tubes which are then firmly sealed 
will in a short time cause them to explode like shells, sending 
the metallic fragments hurtling in all directions with great 
force. 

Although liquid air is as harmless as water, and so long as it 
is not confined, cannot of itself explode, yet it is an extra- 
ordinary fact that, when mixed with other substances, it 
can form an explosive comparable in intensity to dynamite 
itself. Thus, in some experiments carried out by Mr. Trippler 
of New York, a bit of oily cotton waste, soaked in liquid air, 
was placed inside an iron tube open at both ends. This was 
laid inside a larger and stronger tube, also open at both ends. 
When the waste was ignited by a detonating fuse the explo- 
sion was so terrific that it not only blew the smaller tube 
to pieces, but it burst a great hole in the outer one as well. 

Indeed in Germany practical use has been made of this 
fact in blasting in coal mines. Cotton wool impregnated 
with coal dust and steeped in liquid air is rammed into a hole 
drilled in the coal, and the whole exploded by a detonator in 
the ordinary way. The explosion which ensues is as effec- 
tive as a dynamite one, but without its risks ; for should a 
charge fail to explode in a few minutes all danger is past ; 
because there remains only cotton and coaldust when the 
liquid air has evaporated. This is a valuable feature of its 



THE AIR 149 

use, since many lives are lost annually in attempting to 
remove dynamite charges which have for some reason or 
other failed to explode. 

This property of liquid air is due to the fact that it contains 
oxygen in a very concentrated form. When it is mixed with a 
substance which will burn rapidly in oxygen, and a detonator 
is applied to the mixture, an explosively rapid combustion 
sets in, in which the sudden intense heat generated causes 
an instantaneous and violent rush of gas so that the whole 
goes off like so much dynamite. Indeed the actions in both 
cases are much the same, as we shall see when we come to 
deal with the latter body. 

As we have already pointed out, air is composed of twenty- 
one parts of oxygen and seventy-nine parts of nitrogen. It 
begins to boil at— 195 C, the boiling point of nitrogen. 
The nitrogen boils off first, leaving behind the oxygen, 
and so the temperature gradually rises until it reaches 
-183 C. 

The more nitrogen it loses the bluer and at the same time 
the heavier the liquid becomes. This change may be 
shown easily by pouring a quantity of liquid air into a large 
glass bottle partially filled with water. For a moment it 
floats, boiling with great violence, liquid air being slightly 
lighter than water. When, however, the nitrogen has all 
boiled away, the liquid oxygen, being heavier than water, 
sinks in beautiful silvery bubbles, which boil violently until 
they disappear. A few drops of liquid air thrown into 
water will instantly freeze for themselves little boats of ice, 
which sail around merrily until the liquid air boils away. 
In this way ordinary liquid air exposed to the atmosphere 
becomes very rich in oxygen, and oxygen in such a 
concentrated form is a very wonderful substance. For 
instance, ordinary woollen felt can hardly be persuaded to 
burn even in a hot fire ; but if it be dipped in this liquid 
oxygen, or even in liquid air, it will burn fiercely, with all 
the terrible violence of gun-cotton. A splinter of wood, when 
soaked in liquid air rich in oxygen, will burn like a fiery 
torch with immense power, while a glowing wood splinter 
plunged into liquid air bursts into furious flame, and 



150 MODERN CHEMISTRY 

may cause the whole vessel containing the liquid air to be 
shattered by the heat developed. 

Indeed, steel itself may be burnt by liquid air. To demon- 
strate this a tumbler of ice is made, and it is half filled with 
liquid oxygen. A burning match is then attached to a bit 
of steel spring and the whole dipped into the liquid air 
contained in the ice tumbler. The steel then burns, splut- 
tering and giving out a glare of dazzling brilliancy. Between 
the liquid oxygen and the burning steel are about 2,ooo° C, 
and yet the ice tumbler is not affected. The oxygen is 
turned into a gas before combustion begins. For liquid 
oxygen itself probably will not support combustion. Instead 
of a steel spring, an electric-light carbon red-hot at its tip 
will burn in exactly the same way with dazzling brilliancy. 
Thus the abyss of cold which prevails in liquid air 
does not prevent it from acting as a powerful inflaming 
medium. 

Liquid air introduces us to a strange cold world very differ- 
ent from the one in which we live. All things alter their 
properties to an astonishing extent at these low tempera- 
tures, and the exploration of the properties of matter under 
these new conditions is now steadily proceeding in all parts 
of the civilised world. Thus iron and steel increase their 
tensile strength immensely, but at the same time become as 
brittle as glass. 

Seeds have been frozen in liquid air, and even in liquid 
hydrogen, and kept there for months at a time, and yet when 
thawed again they were found to be quite uninjured. On 
being planted they germinated and grew. In the same way 
the most intense cold will not kill many bacteria. Masses 
of deadly bacteria have been frozen for six months at a time 
in liquid air into dense solid masses ; yet when these bacteria 
are carefully thawed they become again active and living. 
Professor McKendrick froze for an hour at a temperature of 
— 182 C, samples of meat, milk, etc., in sealed tubes. When 
these were opened after being kept at a blood heat for a few 
days, their contents were found to be quite putrid, showing 
that the bacteria in them had not been killed by the freezing 
process. Vital matter in this frozen state is neither dead nor 



THE AIR 151 

alive. It is in an intermediate state in which all vital 
activity is suspended. It will keep thus for thousands of 
years unchanged and immobile as a stone, and yet, when the 
right temperature is reached again, it will wake again to life 
and activity. 

Of course this only applies to the simpler forms of life. 
Intense cold will always kill large animals. Thus, a man or 
a pig once frozen stiff into a hard brittle mass in liquid air, 
will never wake again, even if most carefully thawed. 
Still their flesh would keep quite fresh under such circum- 
stances, and, indeed, frozen meat is imported in a quite fresh 
condition into England from all parts of the world. It is 
an interesting fact that in Siberia corpses of the mammoth, 
a kind of hairy elephant which has been extinct for ages, 
have been found buried in the ice, and in as fresh a condition 
as on the very day it sank to die ages ago upon the cold 
cheerless waste of ice and snow. Indeed, men and wolves 
have eaten the flesh of these preserved corpses without 
any ill effects afterwards. 

These facts are of great intrinsic interest. Indeed, Arr- 
henius, the great Swedish chemist, maintains that by this 
means a mighty stream of life is kept circling in space from 
world to world about the whole of the immeasurable universe. 
He believes that tiny germs of life, tiny spores and bacteria, 
are borne to the upper regions of the atmosphere by winds 
and storms, and are thence driven out into the endless depths 
of space by radiation pressure from the sun. They rapidly 
under this influence attain a velocity of hundreds, nay thou- 
sands of miles a second and soon flash away into the utter 
darkness and cold of space. Here for countless ages they 
rush through immense waste spaces. No cold can kill them, 
nor time destroy them,* and so they wander for eternities 
of time chilled to an awful cold of nearly— 273 ° C. ; but at 
last they flash into the upper atmosphere of some distant 
world. Usually such a planet is not in a suitable condition 
to receive them, being either too hot or too cold, and so the 

* It has been suggested recently that the ultra-violet light from 
the sun would kill such life-germs when they reach the confines of 
the atmosphere. 



152 MODERN CHEMISTRY 

germ perishes or lies dormant, perhaps for hundreds of 
thousands of years, until the climate alters and 

" The hour comes to unfold it, and the need." 

Sometimes it happens that they reach a planet in exactly 
the right condition to allow life to flourish. When this 
occurs we get gradually unfolding from this single germ a 
vast scheme of life, evolving into millions of different forms 
and passing in one long never-ending procession, ever from 
the simpler to the more complex, 

" From earth to lichen, herb to flowering tree, 
From cell to creeping worm, from man to what shall be." 

Thus a formerly naked and desolate planet becomes 
covered with tiny microbes and great animals, plants, trees, 
birds and insects, spreading over all lands and seas, struggl- 
ing upwards into the air and penetrating downwards into 
the dark depths of the oceans, and finally culminating in some 
intelligent animal which conquers to itself the whole planet, 
building great cities filled with marvels of art and science, 
and controlling all things with an iron hand. 

In the course of time the conditions on this planet again 
become unfavourable to life ; and it slowly fades away again. 
Silence once more claims its own, and reigns throughout the 
once busy world. Our moon, perhaps, has gone through 
such a cycle of life, and is now a silent lifeless waste. Our 
own world, nay, all the worlds now rushing through space, 
thronged as many of them are with life, must all so perish 
in the course of time, an idea which Tennyson expressed in 
the beautiful lines : — 

" Many a hearth upon our dark globe 
Sighs after many a vanished face, 
Many a planet by many a sun may roll 
With the dust of a vanished race." 

This steady remorseless oncoming of silence over the whole 
visible universe, and its ultimate burial in appalling dark- 
ness, has forcibly struck the imagination of more than one 
poet, a fact expressed by McArthur in his poem termed 
" Silence" : — 



THE AIR 153 

c* Beyond the search of sun or wandering star, 
In that deep cincture of eternal night 
That shrouds and stays this orbed flare of light 
Silence is brooding, patient and afar, 
Secure and steadfast in his primal right, 
Reconquering slowly, with resistless might, 
Dominions lost in immemorial war. 
The thronged suns are paling to their doom, 
The constellations waver, and a breath, 
Shall blur them all into eternity ; 
Then ancient silence in oblivious gloom 
Shall reign — where holds this dream of Time and Death 
Like some brief bubble in a shoreless sea."* 

Although at the present time the air consists mainly of 
four volumes of nitrogen mixed with one volume of oxygen, 
yet the reader must not go away with the idea that the air 
always has had and always will have this composition ; 
for all things are changing, slowly or quickly, and things 
which seem at rest are only apparently so. The air is no 
exception to this general law. It, too, is even at the present 
time changing its composition exceedingly slowly, so slowly 
that in the course of six thousand years no noticeable change 
has taken place. The Greeks and Romans must have breathed 
air of sensibly the same composition as that we now breathe ; 
but the case is very different when we go back, not thousands, 
but millions and hundreds of millions of years. A slow 
continuous change going on for such vast ages can produce 
effects which astonish us by their magnitude. Suppose, for 
example, the amount of oxygen in the air diminished in a 
thousand years by only yoW per cent. This is a rate of change 
far too small to be detected by any measurement that we 
can make. Then in one million years the amount of oxygen 
would have diminished by one per cent, and in only twenty- 
one million years there would be no more oxygen left ! 
Now the earth is, probably, well over a thousand millions of 
years old. In this vast interval of time it may have changed 
utterly and completely the composition of its atmosphere, 
not once, but many times. Indeed, we know for certain 
that ages ago the composition of the atmosphere differed 

* The Century Magazine, Vol. 58 (1898-9), p. 706. Quoted by 
kind permission of Macmillan & Co. 






154 MODERN CHEMISTRY 

entirely from its composition now. At that dim and 
mysterious period of the world's history when the whole 
surface of our planet was a white-hot sea of molten rock, 
the air consisted of steam, carbon dioxide, nitrogen, marsh 
gas, and perhaps hydrogen and helium. The free life- 
giving oxygen, which now maintains untold millions of 
animals in movement and vigour throughout the whole 
world, could not have been present at all in any considerable 
quantity. 

The most astonishing thing about this early atmosphere 
was the enormous amount of that heavy choking gas, carbon 
dioxide, in it. The immense masses of this gas now stored 
up in the interior of the earth in chalk and limestone then 
floated free in the air, filling the valleys and hollows of the 
earth, and sweeping in currents all over its surface. This 
gas alone exceeded in volume the whole present atmosphere 
HUNDREDS of times. Hogbom and Chamberlin, as the 
result of careful calculation, show that the amount of carbon 
dioxide stored in chalk and dolomite must be between 400 
and 600 times the present volume of the atmosphere ! These 
estimates are certainly far too low, because the pre-Cambrian 
limestones were not drawn into the calculation at all. 

The pressures prevailing in this early atmosphere also 
awaken our astonishment. They probably exceeded fifteen 
tons on the square inch or over 18,000 tons on the square yard. 
Under such conditions, and in such an atmosphere, no man 
and no animal such as wanders to-day about the earth could 
exist even for a single minute. 

These conditions did not last very long. As the earth 
cooled the steam gradually condensed to form the oceans 
and seas, while at the same time the carbon dioxide in it 
was gradually absorbed by the cooling rocks, until there 
now remains only a minute trace (0.03 per cent.) in the air we 
breathe. 

We have many reasons for the statement that there was 
no oxygen, or at least very little, in the early atmosphere 
of the earth.* 

* See Phipson, " Researches on the Present and Past History of 
the Earth's Atmosphere," London (1901). Also Arrhenius, " Das 



THE AIR 155 

In the first place, there were on the molten earth such enor- 
mous masses of substances which will combine with oxygen 
that the latter element must have been soon completely 
used up. For example, the amount of free carbon now 
deposited as coal and bituminous matter is enough to combine 
with nearly all the present amount of oxygen in the air — 1,216 
billion tons. Besides this there are large amounts of com- 
bustible iron pyrites, lower oxides of iron, etc., etc. Astrono- 
mical evidence confirms these conclusions. We know, for 
example, that free oxygen occurs in the sun's atmosphere, 
together with enormous excess of hydrogen gas. Now in all 
probability the earth's primeval atmosphere was of a similar 
constitution (since it too was once part of the same primeval 
fiery nebula from which our sun condensed), and contained 
hydrogen in excess. 

As the whole system cooled the oxygen gradually united 
with the hydrogen to form water, leaving behind a great 
mass of free hydrogen floating about in the atmosphere. 
Perhaps also large volumes of hydrocarbon gases, such as 
marsh gas and ethane, were also present in this strange 
early atmosphere, since such gases are found in the comets 
which occasionally enter the solar system. Deadly cyanogen 
gas and vapour of prussic acid were also probably present 
in small amounts. In this weltering storm-shaken mass 
of gas the nitrogen now in the air we breathe was pro- 
bably still present, and on account of its chemical inertness, 
has remained practically unchanged since the very earliest 
ages. Its antiquity, therefore, is enormous. 

Phipson states that many of the higher plants, as well as 
many bacteria, will grow in an atmosphere consisting entirely 
of carbon dioxide and hydrogen. It is consequently possible 
that even in the earliest times there existed simple plants 
long before a noticeable amount of oxygen was present in 
the air.* 

Indeed, the presence of oxygen in the atmosphere was 

Werden der Welten," pp. 46-57 (1908), where the whole question is 
discussed critically in the light of recent researches. 

* To some bacteria oxygen acts as a poison. Such organisms 
can only nourish in oxygen-free media. 



156 MODERN CHEMISTRY 

probably brought about entirely by the vital activity of 
plant-life, which flourished on a vast scale in early ages, 
choking up the whole earth with the ruins of their decay. 
For, as we shall see in the chapter on carbon dioxide, green 
plants feed on the small quantities of this gas in the air, 
decomposing it under the influence of sunlight, retaining its 
carbon and setting free its oxygen. The carbon goes to 
build up the frame of the plant, and the oxygen escapes into 
the air. Arrhenius thinks that the earliest plants, living in 
an atmosphere of carbon dioxide, marsh gas, and hydrogen, 
but devoid of oxygen, gradually set free the combined oxy- 
gen in the manner described, and this, under the influence 
of electric discharges (for this strange primeval world heard, 
too, the roar of thunder and saw the flash of lightning), 
converted the free hydrogen present into water, and oxidised 
the hydrocarbon gases to carbon dioxide and water, until 
they were all used up. For untold aeons of ages millions of 
plants, working silently but ceaselessly, steadily poured 
oxygen into the air until the present constitution was attained. 
No less than 1,216 billions of tons of oxygen were necessary 
to achieve this result, and the power to perform this gigantic 
task was all furnished by the gleaming sunlight of warm 
summers gone and forgotten ages before the foot of man, or 
the sound of human voice disturbed the silence of the 
primeval world ! Botanists assert, however, that a certain 
amount of oxygen is absolutely necessary for the develop- 
ment of plant life. To meet this want Arrhenius supposes 
that when the world first condensed out of the solar nebula, 
it possessed, even in its outermost parts, an exceedingly 
high temperature. Under these conditions the lighter gases 
such as hydrogen and helium gradually flew off into space 
because the earth does not possess a gravitational attraction 
great enough to prevent particles moving with such great 
speeds as the molecules of these gases under the temperatures 
then prevailing from flying off into space. On the other 
hand, there remained behind the heavier gases such as nitro- 
gen and oxygen, their molecular velocity being much less. 
The original excess of hydrogen and helium, therefore, 
vanished before the solid crust of the earth was formed, so 



THE AIR 157 

that in the earth's atmosphere, immediately after the forma- 
tion of the crust, there was present a certain amount of 
oxygen, together with much nitrogen, carbon dioxide, and 
steam. Nevertheless this does not affect the general con- 
clusion arrived at above that the greater part of the oxygen 
in the air was, as Phipson suggested (and before him, Koehne 
in Brussels in 1856), set free by plants decomposing the 
carbon dioxide. 

However this may be it seems certain that tne presence of 
oxygen gas is an essential condition for the coming into 
existence of animal life. Animals are, so to speak, parasites 
which live on plants and absolutely depend upon them for 
nourishment. Plants, on the other hand, need, besides a 
suitable temperature, only carbon dioxide and water, and 
these gases occur in the atmosphere of probably every planet, 
being thrown out as waste products from the cooling masses 
of their inner glowing interior. 

Thus we see that the atmosphere is no inert changeless 
mass of gas ; it is changing now even as we live and breathe 
in it, and it has never ceased to change since that far-off time 
when it whirled as a fire mist through space. As it is at 
present constituted it is the product of long ages of steady 
evolution. The passing wind can relate a story of its long 
journey down the stream of time more wonderful than any 
fairy tale. 

The ultimate fate of the atmosphere is a melancholy one 
to contemplate. It will ultimately vanish altogether from 
off the earth's surface.* There are at least two influences 
which, acting singly or conjointly, will infallibly bring 
about this result. The first of these influences is the cooling 
of the earth's exterior in consequence of a diminution of the 
sun's radiating power. As already mentioned, the atmosphere 
is merely that portion of the original nebula from which the 
world was formed, which has not yet condensed to a solid or 
liquid form owing to the fact that the temperature of the 
earth's surface (being nearly 300 C. above the temperature 
of surrounding space) is still sufficiently high to maintain 

* It is uncertain to what extent the presence of heat-evolving 
radium in the sun and earth will affect this conclusion. 



158 MODERN CHEMISTRY 

it in a gaseous state ; but the temperature of the earth's 
surface is mainly dependent upon the amount of heat 
radiated from the sun. Since the sun itself is a cooling body, 
its heat and light-giving properties must in the course of 
time gradually diminish in strength until they die away 
altogether. Then our luminary will relapse into a state of 
death and the whole solar system will be plunged in utter 
darkness and cold. Hence, as the sun's power diminishes, 
the world will become colder and colder. First, a mighty 
frost will grip the whole world and turn all its waters into 
ice. Then the air will condense, first to a liquid and finally 
to a solid state. This will happen when the temperature of 
the earth's surface falls below — 180 C. This temperature is 
not so enormously remote as is generally imagined from 
those prevailing in the coldest regions of the earth. For 
example, a temperature of— 617 C. has been recently (1905) 
recorded in Bothia (Canada) by Captain Amundsen ; and it 
might well happen that a temperature of — 90 C. occasionally 
prevails at the Pole itself. We have now only to imagine 
an equally great additional lowering of temperature in order 
to cause the air itself to liquefy ! As the world continues 
to cool there will surely come a time when the air will 
begin to condense in the upper regions of the atmosphere 
to vast white clouds composed of droplets of liquid air. 
These sinking downwards will cause the air to be gradu- 
ally deposited in the form of immense shallow seas of light 
blue colour — seas so intensely cold as to burn us like molten 
lead ! These seas will roll over the places where the oceans 
of to-day lie ; but of course the water of the latter will long 
since have been transformed into hard masses of ice, pre- 
senting much the same appearance as marble or quartz, 
and regarded by the shivering inhabitants (if any exist) of 
this land of dreadful cold as a rock. 

All the aqueous conditions of to-day will be exactly 
paralleled by this liquid air. For example, just as we now 
have rain composed of water drops, so then at a temperature 
of — 190 C. we shall have showers of liquid air ! The earth 
will be tipped with white poles of frozen air, forming great 
ice-masses much like our present polar ice-caps, while ice- 



THE AIR 159 

bergs of solid air will float south in its seas of liquid 
air ! 

Last of all, when the temperature falls below— 210 C, the 
air will freeze to a solid layer of an ice-like transparent mass 
about thirty-five feet thick. No gaseous atmosphere will 
then exist upon the earth. This will become an intensively 
cold dark wilderness. Then, after untold ages of ceaseless 
movement and gigantic change, the surface of our planet will 
at last rest in supreme repose, motionless and utterly silent. 
For, in the absence of a gaseous envelope, no moan of wind 
or roll of thunder, no splash of rain, no roar of torrent, no 
sound of voice of man or beast or bird, can pierce the 
blackness of the night and break its everlasting calm. The 
surface of the world will be a vacuum as perfect as that 
prevailing in Dewar's vacuum-jacketed flasks. The stars 
will shine out of a coalblack sky upon a lifeless world, set 
stiff and hard in the rigid grip of death, circulating unseen 
and ghostlike in the darkness around a burnt-out sun. Yet, 
only a few miles down in its interior, in strange contrast to 
the dreadful death-bringing cold of its surface, the gigantic 
furnaces of the deep, immense reservoirs of power and energy, 
will still gleam and glow. So the world will continue for 
long aeons of ages, until its matter dissolves away and rushes 
into the oblivion of the ether, or until it is shattered in some 
mighty cosmical collision and resolved into a glowing nebula 
again, only to begin anew another vast cycle of life. 

Even if the sun maintains its present power of radiation 
indefinitely this will not prevent the ultimate loss of the 
earth's atmosphere ; for it is the intense internal heat of the 
earth which keeps a layer of gas around its surface. Only 
a few miles down the white-hot glowing furnaces effectively 
expel any air or water reaching to such depths. When the 
interior of the earth cools sufficiently (as it must ultimately) 
the whole atmosphere together with the waters will retreat 
into it much in the same way that ammonia gas condenses 
into charcoal or water soaks into blotting paper. 

Thus, as the great world spins through its scheme of ever- 
lasting change, the atmosphere which clothes it round also 
undergoes a series of wonderful and mighty transformations. 



km 



ido MODERN CHEMISTRY 

fraught with the greatest consequence to all things that live 
and move on land and sea. The atmosphere, like all other 
things of nature, has had a wonderful past and will yet have 
a wonderful future. 

It has been estimated that in the heavens shine more than 
a hundred million suns. Many are known, from spectro- 
scopic evidence, to possess systems of planets whirling round 
them. Doubtless all possess one or more such planets. 
There may, therefore, exist hundreds of millions of planets, 
in many respects similar to our earth, scattered through our 
sidereal system. It thus becomes very interesting to inquire 
into the constitution of their atmospheres. 

The first question one naturally asks is, Have they all 
atmospheres like our earth's ? The answer to this is that 
these worlds have atmospheres of almost every conceivable 
constitution. On some of them substances which are the 
most abundant constituents of our atmosphere are entirely 
wanting ; while on the other hand substances existing here 
in our atmosphere in the minutest traces may there be present 
in the greatest abundance. Many of the planets possess no 
atmosphere at all. As we have just seen, one of the essen- 
tial conditions for the possession of an atmosphere is a red- 
hot or white-hot interior — in other words, a degree of internal 
heat sufficient to drive out all gases from the interior and 
maintain them on the surface of the planet. 

It can be demonstrated that there is a critical velocity 
for every globe, such that if a body be projected upwards 
with that critical velocity or any greater one, it will escape 
altogether. Take, for instance, the case of the earth. It 
can be shown that for any globe possessing the exact size 
and weight of the earth, the velocity with which a missile 
would have to be shot upwards so as to effect its escape must 
be about seven miles a second. If the velocity with which 
the body started on its vertical ascent were less than seven 
miles a second, then, after reaching a height dependent upon 
the speed of projection, it will commence to return. If, 
however, the speed be more than the critical value of seven 
miles a second, the body will continue its journey, and the 
attraction of the earth will not be sufficient to recall it. Now 



THE AIR 161 

all the gases which, at some time or other, coat the surfaces 
of planets, must be regarded as composed of a number of 
rapidly flying projectiles, viz., the molecules. If the gravita- 
tional force of the planet is not powerful enough to restrain 
them, the rapidly moving molecules will gradually dart away 
into space and be permanently lost to the atmosphere. 
Only a planet of a certain size, therefore, can retain a gaseous 
atmosphere, a fact, indeed, which is in agreement with 
astronomical observation. 

Dr. Johnstone Stoney has calculated the mass needed to 
secure to a planet the lasting possession of an atmosphere. 
It differs for the different gases ; for the particles of the lighter 
gases travel the more rapidly than those of the heavier gases 
and thus require a greater planetary mass to retain them. For 
example, the earth cannot permanently retain hydrogen 
because a definite percentage of hydrogen molecules at 
ordinary temperatures travel with a velocity greater than 
seven miles a second, the critical velocity of the earth, and so 
they slowly escape into space, until in the course of ages 
practically all the hydrogen has vanished. On the other hand 
the earth is capable of permanently retaining the other 
constituents of its atmosphere, such as oxygen, nitrogen, 
argon, and carbon dioxide. 

The conditions reigning on the moon are very different. 
Here the gravitational attraction is only one-sixth that of 
the earth, and consequently a gaseous molecule possessing 
a velocity of only 1.25 miles a second will fly away from it 
into space. Now the highest temperature of the moon's 
surface (the centre of the full moon) is about 150 C. At 
this temperature the velocity of the hydrogen molecule is 
1.45 miles a second, that is to say, greater than the critical 
speed. Therefore hydrogen must disappear from this part 
of the moon in a steady stream into space, and since hydrogen 
diffuses to this point so long as there is any gas remaining, 
the hydrogen, if it once existed in the atmosphere of our 
satellite, must have very soon disappeared from it. Similar 
reasoning holds for oxygen and nitrogen, and, in a slightly 
less degree, for argon as well. It is therefore no wonder 
that we find no trace of an atmosphere on the moon. In its 



162 MODERN CHEMISTRY 

deeper valleys, and underground caverns, however, there 
may still lurk some dense gases like carbon dioxide ; yet for the 
most part the surface of the moon is in a vacuum as perfect 
as can be produced by our best air pumps. Its bare rocky 
surface is covered with vast craters, surrounded by mighty 
walls of slag and lava jutting up into the vacuum to a height 
of ii.ooo or 12,000 feet. Aqueous vapour plays a great 
part in our own atmosphere. On the moon, however, no 
traces of it are met with ; consequently no mists or clouds 
cling to its valleys and mountain tops, and no rivers or seas 
fill up its low-lying parts. Some recent writers, however, 
have maintained that much of the moon's surface is incased 
m snow and ice. From certain huge ring-craters, such as 
Tycho and Copernicus, snow-white ctreams or rays diverge, 
which, it has been suggested, are ancient glacier streams. 
The whiteness of the great mountain Aristarchus has been 
similarly explained. The flashing back by this peak, of 
earthshine at determinate angles of illumination, has often 
counterfeited the vivid glow of actual eruptions. However 
this may be, there can be no doubt that now, since there is 
no erosion of air or water, repose reigns undisturbed over all 
its surface. 

Venus, being about the same size as the earth, retains the 
same gases. It possesses a lofty and dense atmosphere which 
has been estimated to weigh twice as much as ours. Water 
vapour has been definitely detected in its atmosphere. In- 
deed the planet is wrapped round by vast steam clouds which 
hide its surface from us and prevent us from seeing the rivers, 
continents, and oceans, which doubtless extend far and wide 
underneath them.* 

Arrhenius comes to the conclusion that its average tem- 
perature is about 40 C, and that it is well fitted for life such 
as prevails upon this earth. It may be thronged with living 
forms, with great cities, and intelligent beings, yet so long 
as its vast canopy of cloud covers its surface no human eye 

* Recent observations indicate that one face of Venus is perman- 
ently turned sunwards and is warm, while the other side, away from 
the sun, is dark and cold. If so, terrific winds must rush from the 
hot side to the cold, while most of its waters must have distilled 
away from the sunlit face and condensed as ice on the cold face. 



mm 



THE AIR 163 

can ever hope to obtain an indication of their presence. 
Mars is a small planet possessing only one-ninth of the mass 
of the earth. Its gravitational attraction is somewhat over 
one- third of that of the earth, just sufficient to allow it to 
retain oxygen, nitrogen, water vapour, and carbon dioxide. 
On account of its small mass it possesses a thin but extensive 
atmosphere, of a density about one-seventh that of ours. It 
is more than twice as tenuous as the air at the summit of 
the Himalayas, yet clouds form and mists rise in this thin 
Martian air. During the latter half of October, 1894, an 
area much larger than Europe remained covered with rain 
clouds. In the pure sky the sun shines gloriously, exhibiting 
its coronal streamers and prominences as part of his noontide 
splendour. Atmospheric circulation proceeds so tranquilly 
as not to disturb the repose of a warm land basking in a 
bright sunshine. Water certainly exists in this atmosphere. 
It has been detected by means of the spectroscope ; while 
we can actually see its snowy poles, seas, and great engineer- 
ing works which look like canals, and which Lowell believes 
to be the work of intelligent beings. Vegetation, too, prob- 
ably flourishes on this little globe because the colour of the 
plains and canals alters with the season of the year. Quite 
recently oxygen is stated to have been discovered as a 
constituent of its atmosphere. 

The planet Mercury is small compared with the earth, 
and consequently possesses hardly any atmosphere. Its 
critical velocity is three miles a second, compared with the 
earth's seven. It may therefore contain a very small amount 
of water vapour and the very thinnest of aerial coverings. 

The giant planets Jupiter, Saturn, Uranus, and Neptune, 
seem all to be so hot as to exist in a gaseous or liquid condi- 
tion. Their surfaces are hidden from view by vast clouds 
of condensed steam. These planets are heavy enough to 
retain the lightest gases in their atmospheres. Their upper 
regions may, therefore, consist of hydrogen, helium, nitrogen, 
carbon dioxide, sulphur dioxide, besides, of course, steam. 
Their lower regions are probably white hot and may contain 
gaseous metals such as iron and calcium. The spectroscope 
shows that mysterious elements occur in the atmospheres of 



164 MODERN CHEMISTRY 

these planets which are quite unknown upon this earth. 
Thus an intense red band occurs in the spectrum of both 
Jupiter and Saturn, of wave length 0.000,618 mm., which 
corresponds to no known earthly element. Other new and 
unknown substances gleam forth in the light that Uranus 
and Neptune send us. 

The sun, with a mass nearly 332,000 times that of the 
earth, is heavy enough to control the molecules of the lightest 
gases. Before they can escape their molecules must fly 
with the speed of 391 miles a second. Very few gaseous 
molecules attain such great velocities as these and conse- 
quently the sun's atmosphere is enormous. Its upper regions 
consist of vast quantities of the lighter gases hydrogen and 
helium, as well as a gas still unknown upon the earth, the 
mysterious Coronium, which flares forth a vivid green light 
far above the hydrogen layer. The sun's lower regions con- 
sist of gaseous iron, calcium, magnesium, and other metals, 
for the temperature of the sun is so immensely high that such 
metals boil and vaporise on its surface much as liquid air 
boils and vaporises on our earth. 

We have no knowledge regarding the constitution of the 
atmospheres covering the countless millions of invisible 
worlds of space, worlds that we can never hope to see or 
directly investigate. 

Doubtless some possess atmospheres very similar to those 
surrounding our own earth. Others, however, must possess 
gaseous envelopes quite different from those which clothe the 
planets of the solar system. The mysteries which He hidden 
on these strange and distant worlds are probably more 
wonderful than anything that we can even imagine. 



CHAPTER VIII 

OXYGEN, THE LIFE-SUPPORTING ELEMENT 

Few of the grand truths of science have so forcibly impressed 
themselves upon the imagination of man as the fact that 
every speck of living matter in this wide world of ours is 
ceaselessly burning away. A burning coal or candle van- 
ishes ultimately into the invisible gases carbon dioxide and 
water vapour. By an exactly similar, but slower process of 
combustion, every man and every woman upon this earth, 
every living creature that walks or flies or swims, is passing 
away moment by moment into the same invisible products of 
combustion. It is indeed the heat generated by this slow 
continuous combustion that keeps our bodies warm and 
leads men to compare life to a slow-burning fire. 

The agent which causes and propagates this combustion 
is the oxygen of the air. Upon the presence of this colourless 
invisible gas hangs the whole vast fabric of animal and, 
perhaps, of vegetable life as well. Each breath we draw 
represents the inward rush into our bodies of millions upon 
millions of tiny oxygen atoms, which at once begin silently 
and swiftly to clash against molecules of living matter in 
the blood, and to combine with them, and, so to speak, 
burn them up. Each outward breath also represents a 
similar swift outward rush of myriads of molecular systems — 
the smoke and waste gases from the furnace of our bodies. 
This, one of the most remarkable and mysterious facts of 
life, was long ago beautifully expressed by Holmes in the 
stately lines : 

" God has made 
This world a strne of atoms and of spheres. 
With every breath I sigh myself away 
And take my tribute from the wandering wind, 
To fan the flame of Life's consuming Fire." 

165 



166 MODERN CHEMISTRY 

The most wonderful thing about it all is that although we 
are thus wasting away rapidly into invisible gases, yet all 
the time our individuality remains unchanged. The whole 
matter of our bodies may be, perhaps in five years, burnt up 
and replaced completely atom by atom by fresh matter, 
and yet we remain the same being. Within a few months 
by far the greater part of the carbon of our bodies has been 
evolved as carbon dioxide, and its place taken by fresh carbon 
particles derived from the food we eat, yet we still remember 
the events of years ago, when our bodies were composed of 
an entirely different set of atoms. Though the matter 
forming our bodies is changing ceaselessly, life, the sum of 
its changes, does not appreciably alter from year to year. 
And this, in brief, is the epitome of all life, not only of that 
of the individual, but of that of the race as well : — 

" Still glides the stream, and shall for ever glide, 
The form remains the function never dies, 
While we, the brave, the mighty, and the wise, 
. . . . must vanish. Be it so ! 
Enough if something from our hands hath power 
To live and act and serve the future hour ; 
And if, as toward the silent tomb we go, 
Through love, through hope, and faith's transcendent dower, 
We feel that we are greater than we know." 

In the human body this process of slow oxidation or com- 
bustion is carried out by a very wonderful piece of mechan- 
ism, which we will now proceed to describe. Air containing 
one-fifth of its bulk of oxygen is sucked into the lungs and 
is there brought into contact with the blood. The oxygen 
in the air then combines with the blood and endows it with 
its rich red colour — hence the rosy hue of health. The 
nitrogen, however, is breathed out unchanged, accompanied 
by the products of combustion. 

When the blood loses oxygen it takes a bluish tint seen 
in the veins. The blood, therefore, is the oxygen carrier 
of the body ; and it is the red corpuscles in it which absorb 
oxygen because they contain a substance called haemoglobin, 
which forms a chemical compound with this gas and carries 
it through every part of the body, thus : 

Haemoglobin + Oxygen = Oxy-haemoglobin. 



OXYGEN, THE LIFE-SUPPORTING ELEMENT 167 



This oxy-haemoglobin holds its oxygen only very feebly 
and readily yields it to substances in the blood which need 
it: 

Oxy-haemoglobin ~ Haemoglobin -f- Oxygen. 

This oxidised blood, driven through the arteries by the 
heart, commingles with the living cells, the minute masses 
of living matter, myriads of which form each organ ; the 
blood trickles between the cells through channels as fine and 
as close-set as the pores in unglazed porcelain. The living 
cells in each organ take from the blood the oxygen that they 
require. It is in the cells themselves that the oxidation of 
the food stuffs takes place, and the end result of this oxida- 
tion or combustion is that the carbon (the black element 
contained in coal and charcoal, which appears when animal 
or vegetable matter is charred) is evolved in the form of the 
invisible gas, carbon dioxide, thus : 



C 

Carbon 



+ 



2 

Oxygen 



CO, 



Carbon Dioxide. 



Hence this gas is evolved in the expired air, and, as already 
stated, the warmth of the body arises in part as the result 
of its slow production, which goes on not only in the lungs 
but more or less through- 
out all the tissues of the 
body. We breathe to a 
certain extent through 
the skin itself. What an 
interesting substance is 
this haemoglobin ! The 
physiologists can extract 
it from the blood, and you 
can see it on their micro- 
scopic slides as a mass of 
beautiful reddish crystals, 
some of which are shown 
in the illustration (Fig. 

2Q). When it combines Fig. 29. — Crystals of Oxy-haemogk)bin — 
lorviplv with nvwpn it prismatic, from human blood. (Illus- 
lOOSely Wltn Oxygen It tratiQn frQm H aliburton's Physio- 

assumes a bright Scarlet logy, published by Mr. John Murray.) 




1 68 MODERN CHEMISTRY 

colour. When the oxygen is removed by treating it with 
substances which take it up the crystals assume the bluish 
tint of Haemoglobin. 

Haemoglobin combines not only with oxygen but also with 
other gases such as carbon monoxide and nitric oxide, and 
it is this fact which makes these substances such deadly 
blood-poisons, as we shall see later. 

This wonderful crystalline substance contains carbon, 
sulphur, oxygen, hydrogen, nitrogen, and about 0.4 per cent, 
of iron. One gram of haemoglobin will combine with 1.34 c.c. 
of oxygen. Yet so feebly does it hold this additional oxygen 
that it will stream out of it and escape when the substance 
is placed in a vacuum. The whole of our vital processes 
depend upon this curious compound, and its colour gives 
blood its splendid crimson tint. 

In some other animals, however, it is replaced by other 
respiratory pigments. Thus a green one, chlorocruorin, is 
found in certain worms, and a blue one, haemocyanin, is 
found in many molluscs and Crustacea. The first contains 
iron and the second copper. Think of green or blue blood ! 
The idea seems curious. If we had these respiratory pigments 
in our blood instead of haemoglobin, this fluid would have 
been of a magnificent green or blue colour ! On other worlds 
beings may exist having the most astonishing contrivances 
for absorbing gases from their atmospheres and thus rendering 
the continuous combustion of their bodies possible. Indeed 
a minute study of the wonders of animal and vegetable life 
upon our earth prepares us for undreamt of and hardly 
imaginable devices in other forms of life which have de- 
veloped along altogether different lines on other planets. 
Such secrets, however, will probably remain for ever hidden 
from human scrutiny. 

Thus we see that so far as the animal world is concerned 
oxygen is the chemical centre of Nature. " Without suffi- 
cient oxygen," says Dr. Leonard Hill, " the power of the 
Prime Minister to control the Empire fails no less than that 
of the sweeper to sweep his crossing." It is indeed the 
source of every man's power. Remove it from the air and 
destruction swift and terrible would fall upon living matter 



OXYGEN, THE LIFE-SUPPORTING ELEMENT 169 

as surely as night follows day ; for although a man may do 
without food or drink for days at a time he cannot do without 
that food of foods, oxygen, for more than a few seconds. 
Consequently within five minutes of its withdrawal from the 
vast ocean of gas in which we live the world would be con- 
verted into a vast charnel house ; yet by such an operation 
the surface of the earth would not be apparently changed to 
a being looking down upon it from another planet ; the sun 
would still shine through a smiling blue sky, and the waters 
would still ripple and surge as of old, but the invisible vitalis- 
ing principle would be irretrievably gone from the air. 

Within sixty seconds of the withdrawal of oxygen animals 
would roll in convulsions, rapidly suffocating, and within 
five minutes the whole world would be hushed in death. 
It is true that trees and plants would continue to flourish 
for some days, but they too, according to botanists, need 
some oxygen and would also ultimately perish. The seas 
would become covered with the dead bodies of millions 
upon millions of fishes, suffocated by the failure of oxygen 
dissolved in water, by means of which they breathe. The 
only beings that would continue to flourish in this oxygen- 
free atmosphere would be a few minute bacteria. Indeed 
from them in time a race of beings might evolve which would 
re-people the world anew with organisms capable of flourishing 
under the new conditions. 

Thus our very existence hangs like a thread upon the 
supply of oxygen that we receive minute by minute from 
the air. Yet, so smoothly runs the course of our lives, few 
of us think of this in daily life until it is forcibly brought to 
our notice by some tragic episode, such as a great pit explo- 
sion, like that at Courrieres in 1906, whereby hundreds of 
lives were suddenly annihilated in the dark depths of the 
mine, not by fire or flame, but by the sudden using up of the 
oxygen in the air they breathed as the result of the explosion. 

We must now say a few words about the appearance and 
properties of the element which produces all these wonderful 
results. Oxygen gas looks exactly like ordinary air, and 
except for the fact that it is slightly heavier, there is nothing 
in their physical properties to distinguish between them. In 



170 MODERN CHEMISTRY 

large masses it is blue, and indeed the blue colour of the sky 
has been held by some authorities to be due to the presence 
of oxygen. Yet how strangely different are its chemical 
properties from those of ordinary air ! Things which burn 
but feebly in the ordinary air blaze forth with the utmost 
fierceness when plunged into the pure element itself, emitting 
a dazzling light and generating an intense heat. Many things 
which will not burn in air at all are combustible in oxygen. 
For example, if we take a piece of steel watchspring and, 
after fastening a little sulphur to the end of it and lighting 
it, plunge the whole into a jar of oxygen, the steel instantly 
begins to burn, spluttering and throwing out a stream of 
brilliant sparks. The following change takes place : 

3 Fe -f 20 2 - Fe 3 4 

Iron Oxygen Magnetic Iron Oxide. 

The pale blue feeble flame of sulphur burning in air is 
transformed in oxygen into a magnificent lilac-coloured flame. 
A gas known as sulphur dioxide is produced, thus : 

S + O2 - so 2 

Sulphur Oxygen Sulphur Dioxide. 

Those of you who have only seen a candle burn in the 
diluted oxygen of our air can hardly form an idea of the bril- 
liancy and glory of its flame in pure oxygen, the carbon in 
it burning to carbon dioxide and the hydrogen to water 
vapour. 

Now it is a mere accident that our atmosphere contains 
only twenty per cent, of oxygen. This oxygen was gradu- 
ally set free by millions of plants working ceaselessly for 
untold ages, and had not the vegetative processes been greatly 
diminished from time to time by periods of arctic cold, it 
may well have happened that at the present day the per- 
centage of oxygen in the air had risen to over ninety per 
cent. We should thus have been living in an atmosphere 
of practically pure oxygen. What a vast difference this 
would have made to our lives ! All our domestic arrange- 
ments would certainly have had to be ordered other- 
wise. Think, for example, of the fact that it would be quite 
dangerous to burn either coal or wood or to use iron grates. 






OXYGEN, THE LIFE-SUPPORTING ELEMENT 171 

For these substances would burn so furiously, emitting such 
a dazzling light, and generating such intense heat, that they 
would be all consumed in a few minutes. 

To maintain a coal fire under such conditions would be 
something like maintaining a fire of cotton wool or paper 
under ordinary conditions. Moreover, so tremendous would 
be the heat that the very iron grates which confined the coal 
would melt, catch fire, and burn away like an inflammable 
substance. So that iron boilers, grates, stoves, and heating 
machinery generally would become almost an impossibility 
on this oxygen planet. A house on fire would be altogether 
a terrible affair, for it would blaze up in a few moments and 
shine with the brilliancy of an arc lamp, while molten iron 
streams would come flowing out of the house burning as they 
rolled. I suppose no fire engine in the world could put out 
such a conflagration. 

Tobacco-smoking would certainly have been an unknown 
habit ; for in this fiery atmosphere tobacco would catch fire 
like paper, and disappear in a whiff of furious flame ! 
All this seems very strange, and yet there probably exists 
many a planet where these conditions are fulfilled, and whose 
atmosphere consists almost wholly of pure oxygen gas. If 
in addition the atmospheric pressure of such an oxygen 
planet were much greater than that of our earth, not only 
would these effects be greatly exaggerated, but coal and wood 
under these circumstances would burn so furiously as to 
produce an explosion ! A knowledge of the facts of science 
shows us that the possibilities lurking within this vast uni- 
verse of ours are so strange as to surpass in weirdness any 
fairy tale. 

When oxygen gas is cooled to a very low temperature 
(—•183° C.) it condenses to a beautiful blue liquid whose 
properties were discussed in our chapter on liquid air. 
One strange thing about this liquid is that it is strongly 
magnetic. This may be shown by placing a little 
liquid oxygen in a glass between the north and south 
poles of a powerful electro-magnet, when the fluid is 
seen to be attracted by the poles, heaping up over each 
to an appreciable extent. Here, all unsuspectingly, the 



i;2 MODERN CHEMISTRY 

chemist obtains a glimpse of the vast complexity and 
titanic forces which prevail in the world beneath the atom ; 
for the mere fact that oxygen exhibits magnetism shows that 
its atoms not only have whirling round them with tremendous 
velocities large numbers of negatively charged electrons, but 
that, in the magnetised oxygen at least, these orbits all lie in 
the same plane, like those of the planets in the solar system.* 
The molecules of oxygen, like those of hydrogen, consist 
of two circling atoms, which fly at o°C. with the speed 
of 461 metres a second. The diameter of the molecule 
has been estimated at about 2 x io~ 8 cms. That is to say, 
200 millions placed in a row would just cover the breadth 
of your little finger nail ! and yet objects so tiny are 
themselves great universes, each atom being, according to 
Sir Oliver Lodge, made up of about 30,000 separate electrons ! 
At ordinary temperatures and pressures there exist within 
each cubic millimetre of oxygen gas, that is to say, within 
the volume of a large-sized pinhead, no less than 
42,090,000,000,000,000 molecules. So that oxygen gas is, 
like all the other things of Nature, a very complex thing 
indeed. 

The use of oxygen as a means of allowing men to enter 
into poisonous atmospheres, such as exist in exploded coal 
mines, in stagnant sewers, gasometers, cellars, and under- 
ground places, has lately been brought prominently to public 
notice. In the majority of modern oxygen breathing appar- 
atus the oxygen is compressed in strong steel cylinders often 
to 100 or 120 atmospheres, and is allowed to stream slowly out 
into an indiarubber bag or reservoir, and is thence directly 
breathed through tubes which fit into the mouth. The 
carbon dioxide gas breathed out from the lungs is absorbed 
by means of caustic soda placed in the rubber breathing-bag in 
front. By means of this continual supply of fresh oxygen men 
can advance and work for hours in poisonous atmospheres. 
The illustration (Figs. 30, 31) shows the Fleuss-Siebe-Gorman 
breathing apparatus, which is one of the best of this type. 
Several other excellent oxygen breathing apparatus exist, such 
as the Draeger, but we cannot discuss them here more fully. 

* See Fournier d'Albe, " The Electron Theory," p. 159 (1906). 



OXYGEN, THE LIFE-SUPPORTING ELEMENT 173 

Current literature abounds in cases where oxygen supplied 
in this manner has enabled life and property to be saved. 
One of the earliest cases on record occurred at the Killings- 
worth Colliery in 1882. Eight miners were imprisoned by 
the collapse of a shaft, and the Fleuss apparatus (an older- 
form of that just described) was employed in getting them out. 

Quite recently another case occurred at the Elswick Works 
of Sir W. G. Armstrong, Whitworth and Company.* It 
appears that a workman entered an old tunnel shaft of a 
furnace with the object of repairing it. But the shaft was 
full of poisonous gas, and to the horror of the men above the 
man fell unconscious. Luckily an oxygen-breathing appara- 
tus was at hand, and the poor fellow was, by its means, soon 
pulled out into safety, and was resuscitated by means of 
artificial respiration. 

At a terrible colliery disaster at Reden, in Prussia, a rescue 
party armed with this apparatus saved no less than twenty- 
six lives, while in a similar disaster at Merlach eight lives 
were saved, f 

In this work, however, the rescuers themselves run a con- 
siderable risk. Thus at the fearful Courrieres disaster in 
1906, where a terrible explosion shattered the great mine 
and rilled the workings with poisonous gas, no less than 1,100 
men perished, principally by suffocation. A rescue party 
breathing oxygen advanced into the black shattered depths 
to search for men still living. When in the midst of the 
frightfully poisonous atmosphere the oxygen of one of the 
rescue party began to fail, and in desperation he tore off 
his helmet, probably scarcely realising the danger of so 
doing. The unfortunate man immediately fell unconscious, 
and before the body could be brought out life was extinct. 

Recently another rescuer lost his life in the sad Ham- 
stead disaster, near Birmingham, in March, 1908. This 
case is of interest because it shows what rescue apparatus 
can do in enabling men to penetrate places in which no living 
being could otherwise exist for a single minute, and we will 
therefore give a fuller account of it. A candle left carelessly 

* Trans. Inst. Mining Engineers, 1907, Vol. 35, p. 224. 
t Ibid., Vol. 37, p. 83. 



174 MODERN CHEMISTRY 

about caused the woodwork at the foot of the main shaft to 
catch fire. Immediately there was a great conflagration, and 
a few miners dashing through the flames managed to reach 
the cage and were hauled safely to the surface. The others, 
to the number of twenty-five, found their retreat cut off by 
a wall of advancing fire and fled into the depths of the mine, 
where they were suffocated by the poisonous fumes evolved 
from the burning coal. Above the shaft the greatest excite- 
ment prevailed, and rescue parties armed with oxygen- 
breathing apparatus descended into the burning mine. The 
conditions of work were terrible. The workings of the mine 
where plunged in absolute darkness, and the dense smoke 
from the burning coal and woodwork scarcely allowed the 
rescuers even with their electrical lamps to see more than a 
yard or so in advance. They bravely groped their way 
onwards until they had penetrated nearly half a mile into 
the workings, but here they were stopped by a terrible heat 
and smoke. As time wore on the fire spread, and a large 
part of the mine became a fiery furnace. An illustration 
in the Graphic, March 14, 1908, shows a party of the 
rescuers armed with the Draeger oxygen-breathing apparatus 
groping their way forwards into the burning depths. 
Several desperate attempts were made to advance, and 
it was in one of these that the rescuer Welsby lost his 
life. He fell unconscious while working nearly half-a- 
mile from the foot of the shaft. Whether it was that 
his oxygen gave out or whether the terrible heat in the con- 
fined space in which he worked occasioned a fainting fit will 
now probably never be clearly established. He was working 
in company with a man named Whittington, and the latter 
carried and dragged his mate for some distance at the immi- 
nent risk of his own life until his supply of oxygen had also 
nearly spent itself, and he was forced to struggle back to 
the cage. He, too, would have fallen a victim had he not 
been found by a comrade. All subsequent efforts to reach 
the heroic Welsby proved unavailing. After hundreds of 
tons of water had been poured into the mine another 
attempt was made to enter it, but by this time the fire had 
spread so terribly that it was now impossible to reach even 



OXYGEN, THE LIFE-SUPPORTING ELEMENT 175 

the bottom of the shaft. Now although in this case no lives 
were actually saved, and one was actually lost, yet we have 
a demonstration of the fact that men could travel and work 
for hours in a burning mine every part of whose interior 
was filled with frightfully poisonous gas, so poisonous, indeed, 
that a few mouthfuls would have probably been fatal. 

A great many collieries are now provided with these appa- 
ratus, and by their prompt action fires in mines can be 
stopped. Once a small fire begins in a mine the air becomes 
so bad that men cannot approach it to put it out and so it 
gradually grows into a vast conflagration ; but provided 
with these oxygen-breathing apparatus the men can advance 
promptly and dam up the workings and then extinguish 
the fire by pouring water on the blazing coal. 

Perhaps the most sensational use ever made of an oxygen- 
breathing apparatus was that made by Mr. Fleuss when he 
saved the Severn Tunnel from flooding in 1880.* It appears 
that while the men were tunnelling deep under the Severn, 
a flood of water suddenly burst into the tunnel from 
some subterranean spring. Panic seized the workmen, and 
they fled with the water roaring after them, and only narrowly 
escaped with their lives. Now, in order to provide for such 
a sudden disaster, an iron door had been constructed by the 
engineers, which could hermetically close the passage, and so 
prevent the water from progressing further. The men, 
thinking that the whole Severn river was pouring in upon 
them from the fractured wall, fled without closing this door. 
The consequence was that in a few hours the workings had 
been drowned completely, the water standing 150 feet deep 
in the shafts. Great pumping engines were erected and ulti- 
mately the level of the water was reduced to thirty-nine 
feet in the shaft. Further it was impossible to go. 

The only hope of success lay in closing the iron door, and 
so stopping the inward rush of water. To do this a diver 
had to descend into thirty-nine feet of water, and then creep 
along a passage all under water and in absolute darkness 

* See Trans. S. Wales Mining Institute, 1880, Vol. 12, p. 100, and 
PP' 35°. 35*« A popular account is given in " Engineering Wonders 
of the World," Part II., pp. 83, 84. (Nelson & Son). 



176 



MODERN CHEMISTRY 



for the fifth part of a mile before he reached the door at all. 
Moreover, the way was jammed up with two trams, over 
which it was necessary to crawl in the dark, and remove 
some metal rails which had caught in the door and prevented 
it from shutting. The diver Lambert first started on his 




Fig. 30. — How the Severn Tunnel was Saved from Flooding in 1880 by the 
use of compressed oxygen attached to a diving suit. A sudden inrush 
of water having flooded the workings it became necessary to send down 
a diver to close a certain water-tight door which would stop the inrush 
of water. Ordinary diving suits were inapplicable on account of the 
weight of the air-tubes. The, at that time, recently-invented Fleuss 
Oxygen-breathing Diving Apparatus, which was an ordinary diving suit 
carrying a supply of compressed oxygen on the back, enabled the diver 
Lambert to walk over 1,020 feet along the drowned passage, climb over 
two overturned waggons which blocked the road, and close the door. 

perilous journey in an ordinary diving suit, and, armed only 
with a short iron bar, groped his way carefully yard by yard 
in total darkness over the debris which strewed the floor, past 
overturned waggons, lumps of rocks, and tools which had 
been cast away by the workmen as they fled. He actually 





Fig. 31. — The Oxygen Breathing Apparatus (Fleuss-Davis patent). 

A supply of compressed oxygen is contained in the cylinders on the back. By means of a 
screw-valve situated at the side the oxygen is allowed to flow out in a steady stream into a 
strong rubber breathing-bag in front. From this two tubes lead to the mouth of the wearer. 
Both are fitted with mica valves, so that in the one oxygen gas can only pass inwards from 
the bag to the lungs of the man, and not in the reverse direction. In the other oxygen can 
only pass from the mouth of the man into the bag. The one tube serves to supply the 
wearer with a steady stream of fresh oxygen to breathe, while the other tube carries away 
the oxygen breathed out from the mouth. The bag contains caustic soda, which absorbs the 
carbon dioxide in the exhaled gas, and renders it fit for use again. Wearing such an 
apparatus, it s possible to work lor two to three hours in a poisonous atmosphere and thus 
rescue men suffocating in an exploded mine or overcome by fumes in underground places where 
foul air collects. The gauge attached to the oxygen cylinders allows the wearer to read off 
how much oxygen is still contained in them, 

(Illustrations from a pamphlet sent tbe author by Siebe, Gorman & Co., "Neptune Works," 
187, Westminster Bridge Road, London, S.E.) 

Face page 176, 



OXYGEN, THE LIFE-SUPPORTING ELEMENT 177 

reached to within 300 feet of the door, but further he could 
not go, as he found that it was impossible to drag over 1000 
feet of air hose after him, as it floated to the roof, and its 
friction against the rock and rough timbering offered greater 
resistance than he could overcome. After several efforts, 
even with two men passing the hose along, he abandoned 
the attempt, and was obliged to return to the shaft defeated. 
The difficulty was solved by the " Fleuss " diving appara- 
tus, which consisted of an ordinary diving suit carrying on 
its back in a steel cylinder a supply of compressed oxygen, 
thus making the diver independent of the long, cumbrous, 
heavy air tube. The diver breathed through a purifier 
containing caustic soda to absorb the carbonic acid or carbon 
dioxide which is being continually exhaled from the lungs 
into an air space contained in a waterproof jacket. Into this 
space oxygen gas was admitted from time to time from the 
cylinder of compressed oxygen, thus making the diver quite 
independent of any external supply. Mr. Fleuss, the 
inventor, first descended, but not being a professional diver 
was unsuccessful. Afterwards the diver Lambert made the 
attempt with the new apparatus, and after two journeys 
succeeded in closing the door. We can well imagine with what 
relief the anxious watchers at the shaft mouth at last saw the 
sudden appearance above the water of the bold adventurer 
after an absence of one and a half hours. How great a danger 
he ran may be appreciated from the fact that when Lieuten- 
ant Damant was testing this apparatus for the Admiralty 
Committee, and was deep under water, he suddenly swooned. 
The reason was that he had unwittingly let the oxygen per- 
centage fall too low, and had fainted away without realising 
his dangei Before he could be got out of the water and freed 
from the apparatus his breathing had stopped, and he was 
apparently dead ; but the prompt application of artificial 
respiration soon brought him round. Had such an accident 
happened to Fleuss or Lambert when in the dark reaches 
of the tunnel nothing could have saved their lives. It is 
needless to say that in the thirty years which have elapsed 
since Mr. Fleuss invented this apparatus great improvements 
have been introduced, and this danger is now surmounted. 

M 



178 MODERN CHEMISTRY 

Oxygen has other uses besides those of restoring flooded 
tunnels and exploring exploded mines. It is one of the most 
valuable foods which can be given to an athlete undergoing 
violent exertion. For easing distressed breathing and the 
furious beating of the heart after a great muscular effort it 
is unsurpassable. The reason is not far to seek. A man at 
rest requires oxygen to burn the oxidisable matter in his 
blood and cells. When the man begins to work hard, oxidisa- 
tion begins to take place at an increasing rate throughout 
all the tissues of his body, and may increase six or sevenfold. 
In order to meet this want, the lungs at once begin to draw in 
deeper and more rapid breaths, and at the same time the 
heart begins to pump more and more rapidly the blood 
into the tissues, and thus supply them with the increased 
amount of oxygen they require, the blood being, as above 
explained, the great oxygen carrier of the body. 

In spite of all these efforts the body sometimes cannot get 
enough oxygen, and the muscles and heart become clogged 
with incompletely oxidised material. In consequence the 
limbs grow weak, breathlessness increases, and the heart is 
overtaxed by its desperate effort to pump in air rapidly 
enough to supply the furnace of the body. All this, however, 
may be altered by allowing the athlete to breathe, immedi- 
ately before or after a great physical exertion, pure oxygen gas 
direct from an oxygen cylinder. The blood sucks in eagerly 
an extra supply of the gas, breathlessness vanishes, and an 
exhausted man is at once revived and sent back into the arena 
full of fire and energy. It is for this reason that oxygen is 
now supplied to boxers and footballers in the breathing 
intervals. Indeed, it is oxygen that the body naturally 
wants, and an artificial supply of pure oxygen will enable 
imperfectly trained men to perform feats which in its 
absence could only be performed by trained athletes. 
Moreover, a supply of oxygen immediately administered after 
a race will rapidly revive a " done " man and allow him to 
feel no injurious effects after the exertion. 

One of the first men to obtain pure oxygen gas was Joseph 
Priestley. So long ago as 1774 he prepared it by heating red 
oxide of mercury by means of a burning glass. He, too, was 




Fig. 32. — Dr. Leonard Hill administering oxygen. 

{From the cartoon by Charles Ambrose,) 
The oxygen is contained in a steel cylinder under a pressure of 100 atmospheres. From this 
it streams into a rubber breathing-bag and is inhaled through a tube passing from the bag 
into a cloth which covers the breather's head. 

Face page ITS. 



OXYGEN, THE LIFE-SUPPORTING ELEMENT 179 

the first to breathe this wonderful gas, which he called 
" dephlogisticated air." He says, "My reader will not 
wonder that, after having ascertained the superior goodness 
of dephlogisticated air by mice living in it, and other tests 
above mentioned, I should have the curiosity to taste it 
myself. I have gratified that curiosity by breathing it, 
drawing it through a glass syphon, and by this means I 
reduced a large jar full of it to the standard of common air. 
The feeling of it to my lungs was not sensibly different from 
that of common air, but I fancied that my breast felt pecu- 
liarly light and easy afterwards. Who can tell but that in 
time this pure air may become a fashionable article in luxury. 
Hitherto only two mice and myself have had the privilege 
of breathing it." How prophetically true were these last 
words of his have been seen above, for oxygen is already 
beginning to be used as a restorative and for many other 
purposes. 

A large number of substances give off oxygen when heated. 
Among them may be mentioned red lead, mercuric oxide, 
potassium chlorate, barium peroxide, etc. It is usually 
prepared in the laboratory by heating potassium chlorate, 
when the following change occurs : 



2KC103 


2KC1 


+ 


30 2 


assium Chlorate 


Potassium 
Chloride 




Oxygen. 



The illustration (Fig. 33) shows the usual method of pre- 
paring this gas as carried out in the laboratory. If pure 
potassium chlorate is taken the salt melts at 372 C. and 
immediately after this the oxygen begins to be rapidly 
evolved. If, however, the chlorate be mixed with only one 
quarter its weight of manganese dioxide, a black substance, 
the oxygen is evolved nearly twenty degrees C. lower. At 
the end of the experiment the manganese dioxide remains 
unchanged. Its action is "catalytic"; in other words, it 
causes an unlimited amount of decomposition in the neigh- 
bouring chlorate without itself undergoing any noteworthy 
amount of change — a very mysterious and as yet scarcely 
understood phenomenon. 



180 MODERN CHEMISTRY 

The largest preparation of oxygen on record occurred on 
May 12, 1899, at Kurtz's Chemical Works at St. Helens in 
Lancashire, owing to an accidental heating of potassium 
chlorate. This substance is in itself harmless enough, but 
since it evolves readily on heating a large amount of pure 
oxygen gas, in which wood and even iron burn with the 
utmost fierceness, it may easily act as an inflaming if not 
an explosive agent. Now in this factory some hundreds of 
tons of chlorate were prepared weekly, and about 150 tons 
of the material packed in casks were lying stored in the build- 
ing awaiting shipment. Somehow or other a spark from a 
cask which was being rolled into one of the crystallising rooms 
alighted on the wooden casing of a crystallising tank in which 
many tons of chlorate were lying. This wood, being soaked 
in dried potassium chlorate solution, was in a highly inflam- 
mable condition. Immediately a furious fire broke out, 
which flared upwards, and in a few minutes the roof of the 
building was blazing. Then followed a terrible and unfor- 
gettable scene. The fierce heat beating upon tier after tier 
of closely packed casks of chlorate caused an enormous 
volume of pure oxygen gas to come rushing forth. All the 
woodwork, being thus supplied with an atmosphere of pure 
oxygen, burned furiously, and the whole building was soon 
white hot, burning with the dazzling brilliancy of a blast 
furnace. At last, the oxygen being unable to release itself 
from its prison fast enough, the chlorate exploded. And 
what an explosion ! Two stupendous swiftly-following 
thunder claps informed the busy town that a disaster had 
occurred, while a pall of black smoke rising upwards like 
a gigantic pillar announced the locality. The works were 
blown to pieces. Buildings and storehouses were levelled 
to the ground.^ Great iron travelling cranes were smashed 
like matchwood. The top of a neighbouring gasometer 
was torn to pieces, and a quarter of a million cubic feet of 
gas rushed flaming forth into the air. The flying burning 
fragments of timber had caused it to ignite, and there was 
seen the appalling spectacle of a vast column of flame 500 
to 600 feet high ascending to heaven with a mighty roar. So 
terrible was the shock that the ground trembled like an 



OXYGEN, THE LIFE-SUPPORTING ELEMENT 181 

earthquake for miles around, houses were blown down, and 
windows miles away were smashed by the gigantic sound 
waves, while the whole town was plunged into a panic. The 
passengers of a train which had just steamed into the station 
had an alarming experience. Although a considerable 
distance away from the scene of the explosion, the carriages 



Ox/gen 




_3 

o s. 

o rn 
0' s 

0» — -; 

-lO -II 



°*y&* 



Water 







Fig. 33. — Preparation of Oxygen Gas by Heating Potassium Chlorate. 
Potassium chlorate, mixed with one quarter of its weight of manganese 
dioxide, is placed in the flask and gently heated. Oxygen gas is 
\apidly evolved and is collected over water in the glass bottle. 

oeemed to be lifted from the metals and the windows 
of the station buildings were smashed as if some one had 
dealt them a sudden blow. Five men were killed out- 
right, while a score or more were badly injured by flying 
debris. The loss of life would have been fearful had it not 
been for the fact that, fearing explosion, the workmen had 
been all hurried away the instant the fire broke out. 

Probably nearly one and a half million cubic feet of pure 



183 MODERN CHEMISTRY 

oxygen gas was thus suddenly poured into the air. It was 
simply the repeating on an enormous scale of one of the experi- 
ments carried out by every beginner in chemistry, namely, 
the preparation of oxygen by heating potassium chlorate. 
Few who have carried out this experiment many times have 
ever realised the consequences of repeating it on such an 
enormous scale. Once the mighty forces which he locked 
up in every chemical compound have got out of control 
disaster in some form or other is always sure to follow. 

The air consists of oxygen diluted with about four times its 
volume of nitrogen, and it is from this practically limitless 
source that oxygen gas is now manufactured. The difficulty, 
of course, is to separate it economically from the admixed 
gases. When liquid air is allowed to evaporate, the nitrogen, 
being the more volatile constituent, boils away more rapidly 
than the oxygen, and the residual liquid becomes continually 
richer in the latter element. This may be shown easily by 
placing some liquid air in a suitable vessel and allowing it 
to evaporate. At first the vapour which rises from the 
liquid air is practically pure nitrogen, and extinguishes a 
glowing wood splinter. Afterwards it gives place to oxygen, 
and the vapour will now cause the same splinter to burst 
into flame. 

It is quite possible to get a richness of, say, sixty per cent, 
of oxygen in this way, but when the evaporation is pushed 
beyond this limit, the vapours which pass off contain so 
much oxygen that in the end when the purity is high the 
liquid itself is almost exhausted, and though what 
remains is practically pure oxygen, its quantity is so minute 
as to render the process useless for commercial purposes. 
It was not until 1902 that Linde perfected a process 
which has enabled oxygen sufficiently pure to be ob- 
tained on ajfcommercial scale by liquefying air. At the 
present time in England alone something like 100,000 cubic 
feet of oxygen are produced daily by this method, and no 
doubt this production will in time increase as the use of 
oxygen augments until it will swell into an immense 
industry. 

Linde carries out the mechanical separation of air into 



OXYGEN, THE LIFE-SUPPORTING ELEMENT 183 



Comb^ssed Air entering at 
200 &LmosJGJur&s and 15°^ 



Pure 
Nifroaen 
at i5 e c 



H 



arid dirnos^hoic 
j^re^ur-e 




Pure Oxygen 
— » aT )5°c ar\d 



Liquid Aw. 



Fig. 34. — Linde's Apparatus for separating air into pure oxygen 
and nitrogen. 

oxygen and nitrogen as follows : * Air compressed to 200 
atmospheres enters a tube which divides at a (Fig. 34) into two 

* In connection with this the reader should turn back and read 
the account of the Linde Process for liquefying the air, as described 
in Chapter VII. 



i8 4 MODERN CHEMISTRY 

counter-current tubes which unite again at b ; it then streams 
through a spiral S in the collecting vessel V, and then passes 
through the regulating valve r, and expands at E into the 
collecting vessel. By the expansion great cold is produced, 
and the chilled gas then streaming up the counter-current 
tubes N and O cools down the incoming stream of air which is 
coming down pipes in their centres. The air thus cooled in its 
turn expands at E and produces a still greater degree of cold, 
which then streams off through N and O, and still further 
cools down the air in the interior tubes. The effect is cumu- 
lative, and ultimately the air expanding at E becomes so cold 
that part liquefies, and dropping into the chamber V parti- 
ally fills it. But another part (principally the more volatile 
nitrogen) passes up through the counter-current tube N and 
leaves the machine. The spiral S also plays a most important 
part, since by its means the continual stream of compressed 
air entering the apparatus gives up nearly all its heat to the 
liquid air in the vessel and causes it to continually boil and 
evolve nitrogen vapour, leaving more or less pure oxygen 
behind. The regulating valve r 2 allows the liquid oxygen 
left behind in V to pass out of the chamber in such a manner 
that the level of the liquid can be altered as required, and 
thereby the quantity of heat imparted to it by the inrushing 
air in the spiral varied so as to maintain the rate of boiling 
of the liquid in V at any given speed, and so obtain oxygen of 
any given degree of purity. The liquid streaming out through 
r 2 (more or less pure oxygen) passes into the counter-current 
tube O, and takes up from the entering air the heat which is 
necessary to cause evaporation and to neutralise its tem- 
perature. If things are properly regulated, the entering air 
gives up almost all its heat to the outstreaming oxygen and 
nitrogen, and these latter gases pass out into the atmosphere 
in a separated condition at temperatures only very slightly 
lower than that at which they entered. In this manner there 
is little loss of heat, and consequently oxygen can be produced 
quite cheaply. From one ton of coal burnt in the steam 
engine generating power something like one ton of oxygen and 
four tons of pure nitrogen can be obtained. 

The apparatus that we have sketched above only illustrates 



OXYGEN, THE LIFE-SUPPORTING ELEMENT 185 

the principle of Linde's invention. In practice extensive 
coiling and fractionating apparatus is required in order to 
produce a complete separation. The straight tubes in our 
diagram are replaced by long spirally-coiled tubes hundreds 
of yards long. Naturally all the tubing must be most care- 
fully packed in wool or feathers in order to prevent external 
warmth filtering through and heating the cold gases. The 
reader who requires a more extended account of these wonder- 
ful new methods may consult Linde's original patent, No. 
14,111 of 1902. The Linde plant is also very clearly and 
concisely described in a book on refrigerating machinery 
recently published by Professor Ewing.* 

No one can contemplate the enormous masses of oxygen 
which occur in Nature without a feeling of astonishment. It 
surrounds us on all sides. Millions upon millions of tons of 
it blow in our faces in the winds which rush over the surface 
of the earth. The whole crust of our globe is saturated 
with it. Originally the whole of the 1,200 billion tons of 
oxygen in the air was locked up in the state of chemical com- 
bination, and it was only set free by cosmic forces work- 
ing for untold ages. And thus it comes about that the quan- 
tity of oxygen occurring in the atmosphere, vast, indeed, as 
it seems to us, is negligible when compared to the enor- 
mously greater masses which occur chemically combined 
in the earth's crust. The chief mass of the latter is composed 
of very old crystalline rocks, the silicates, and these contain 
forty-four to forty-eight per cent, of oxygen. The percent- 
age is still greater in sedimentary rocks like limestone, chalk, 
marble, dolomite, where it sometimes rises from forty-eight 
to fifty-two per cent. Thus we see that all the millions upon 
millions of tons of hard rocks which go towering up to heaven 
in mighty mountain ranges and cliffs are nearly half oxygen 
by weight ! % When we think of the stupendous mass of 
rock and earth lying round the whole earth and extending 
into its depths for miles, the amount of oxygen thus stored 
up about us is seen to be almost unthinkably vast. I sup- 
pose the amount could be calculated in tons weight, but it 

* " The Mechanical Production of Cold," by J. A. Ewing, F.R.S. 
Cambridge University Press, 1909.) 



186 MODERN CHEMISTRY 

would form an almost unmeaning array of figures. But 
oxygen not only forms nearly half the weight of the soil and 
rocks, it forms almost the entire bulk of the sea. Out of every 
ioo tons of water no less than eighty-six tons are oxygen. 
The amount of oxygen thus stored up in the stupendous mass 
of sea-water which girdles this planet with a garment of 
green is immense, and enormously exceeds the amount of free 
oxygen in the air. Hence we see that important as the 
oxygen of the air seems to us, it is only, so to speak, a mere 
accidental trace, an infinitesimal residue, left over in con- 
structing the giant building of the earth. Since man and all 
animals depend essentially for life and existence upon the 
oxygen of the air, these facts give us an insight into the 
general insignificance of the animal world in the design of 
Nature. Undoubtedly we attribute too much importance 
to living matter, as is seen by the vast bulk of non-living as 
compared to the infinitesimal trace of living matter in the 
universe. It must be boldly confessed that Science, in spite 
of her great discoveries, is completely in the dark as regards 
the object and drift, the why and wherefore, of all the great 
workings of Nature. In Tennyson's beautiful words : 

" The drift of the maker is dark, 
As Isis hid by the veil ; 
Who knows the ways of the world, 
How God will bring them about ? " 

Oxygen forms, according to a careful calculation of Clark, 
47.3 per cent, of the earth's crust, and is by far the most 
abundant and widely distributed element in the outer parts of 
the earth. On the other hand, it occurs either not at all, or 
only in traces, in the intensely heated core of the earth, and 
so is probably not the most abundant element of the globe. 

For a long time oxygen could not be discovered in the sun, 
nor in the stars, and men were already beginning to flatter 
themselves that by a special favour of the Creator this planet 
had a monopoly of free oxygen ; but, as is always the case 
with such self-laudatory dogmas, it was soon found that this 
was not the case, for it has been recently shown that it exists 
free in certain stars. In general, however, oxygen emits a 
light which makes it very difficult to detect in the presence of 



OXYGEN, THE LIFE-SUPPORTING ELEMENT 187 

large numbers of other elements. The absence of indications 
of its presence in the light of many stars probably does not 
mean that it is really absent, but merely that its light is 
hidden or suppressed. In the real oxygen stars it must 
occur in appalling excess, and when such stars cool down they 
may well form worlds surrounded with an atmosphere of 
nearly pure oxygen gas. Doubtless even at the present time 
there go circling round them planets whose atmospheres are 
practically pure oxygen, and which, therefore, would be 
capable of exhibiting all the wonderful effects of combustion 
in pure oxygen to which we have alluded in a previous page. 

Under the influence of an electric discharge oxygen 
passes into a most remarkable modification called ozone, 
whose molecules consist of three oxygen atoms. This is very 
chemically active, and at a low temperature condenses to 
a deep blue explosive liquid. 

On our earth almost all the free oxygen occurs as ordinary 
oxygen gas, i.e., as diatomic oxygen, only traces of mona- 
tomic and triatomic oxygen being met with ; but the reader 
must not conclude that this is the case everywhere throughout 
the universe. On other planets where other conditions 
prevail most of the free oxygen may occur as ozone, and our 
ordinary diatomic oxygen may appear to the inhabitants of 
these bodies as a rare and unstable modification. At low 
temperatures and pressures the stable form of oxygen is 
ozone, especially in the presence of moving charges of elec- 
tricity. Now vast discharges of electricity are ever occur- 
ring in the air. The aurora borealis and the numerous 
thunderstorms which occur over the whole earth are but 
slight external manifestations of the tremendous silent dis- 
charges continually rushing through the upper regions of the 
atmosphere. In fact, the whole earth is bathed in a mighty 
torrent of negatively charged particles shot out from the 
sun. It has been for ages revolving in this immense stream 
of negative electricity, and consequently possesses a negative 
potential of a billion volts and an enormous charge of free 
negative electricity. On other planets these electrical 
discharges may be on an incomparably greater scale. • 

Now, if such a planet possessed an atmosphere of oxygen 



1 88 MODERN CHEMISTRY 

at a low temperature and pressure, the whole of this elemen. 
would pass ultimately into the state of ozone, as Goldstein 
showed in 1893. This opens out some amazing possibilities. 
The ozone would thus act as a trap for storing up part of the 
electrical energy flowing past the planet, and on such a world 
it would perhaps condense to great indigo-blue seas, while 
blue clouds and mists of ozone vapour would float about in 
its atmosphere. The sun, if one existed, would shine through 
a sky of a dark blue colour and would probably itself look 
blue. Indeed, the whole surface of such a world would look 
like a landscape viewed through blue glass. Strange forms 
of life, too, would conceivably exist, for the great chemical 
activity, combined with the great energy stored up in ozone, 
could support the energy transformation which is always a 
concomitant of vital action. For the slow passage of ozone 
into ordinary oxygen in the bodies of such creatures would 
supply vital energy to them in much the same way that the 
slow passage of oxygen into carbon dioxide supplies energy to 
us. Both chemical changes are accompanied by the evolution 
of much heat. Perhaps, indeed, in the ages still to run, when 
the world is much colder and darker than it is at present, and 
the seas are all frozen into solid rocklike masses of ice, most 
of the oxygen of our atmosphere will have become ozone, and 
the only living creatures still existing would be some strange 
beings breathing and living on this ozone in the way suggested. 
This opens out still other curious possibilities. The ozone 
which thus gradually accumulated could cause great catas- 
trophes. The stupendous energy stored up in the seas and 
vapours of ozone might be suddenly liberated by the impact 
of a stray meteorite flashing down from the heavens, or by 
a volcanic eruption flaring forth from the bowels of the earth. 
There would then result a vast explosion, extending all 
round the world and annihilating in a second in a vivid flash 
of flame every living creature. The ozone would thus be 
suddenly and entirely transformed into oxygen, which would 
in the course of long ages again be transformed into ozone 
by the slow inpourings of electrical energy, and this again 
would ultimately blow up. Such a planet under these con- 
ditions would thus be the scene of gigantic periodic explosions. 



CHAPTER IX 

THE ELEMENT NITROGEN 

The element nitrogen, the seemingly inert constituent of 
the atmosphere, of which it forms more than four-fifths by 
volume, is of extraordinary importance to man. Besides being 
the parent element of the innumerable drugs, medicines, 
dyes, and explosives used in our complex civilisation, it is 
also an essential constituent of all living matter, which indeed 
owes its sensitiveness and liability to change to the presence 
of unstable nitrogen compounds. In many respects it 
stands apart from the other elements. Its great chemical 
inertness towards the more common and usual elements has 
in the past prevented it from being stored up to any consider- 
able extent in the interior of the earth. It occurs free in the 
atmosphere merely because it is an unusable residue left 
over in the building up of the framework of the earth. Had 
nitrogen been to any important degree a chemically active 
body, then, as has happened in the case of nearly all the 
other elements, it would long ago have been fixed, chemically 
combined, in the soil and rocks, and there would have been 
at the present time scarcely any atmosphere to speak of for 
us to live in. 

However this may be, we must now give a brief account 
of the preparation and properties of this remarkable element, 
and at the same time we will review the great economic 
problems opened within the last few years by the possibility 
of its partial exhaustion in the soils of civilised lands. 

If ordinary air be passed through a red-hot tube filled 
with copper turnings, a sample of impure nitrogen will 
be obtained, because the copoer removes all the oxygen 
from the air, thus : 

2Cu -f 2 2CuO. 

Copper Oxygen Copper Oxide, 

189 



igo MODERN CHEMISTRY 

There then issues from the end of the tube a mixture of 
nitrogen and argon, both inert gases which resemble each 
other and are difficult to separate by purely chemical means. 
They can, however, be separated by liquefying the gas and 
then allowing it to boil. The nitrogen, being more volatile 
than argon, boils away first, and may be collected. The 
argon remains behind in the higher boiling part. Usually, 
however, we do not trouble to free nitrogen from its contained 
argon, since these elements do not interfere with each other's 
reactions. 

A very simple way of removing oxygen from the air is to 
burn phosphorus in a closed bell jar over water. The phos- 
phorus (a piece about the size of a pea will do) is placed in a 
little porcelain basin and lighted by touching it with a piece 
of red-hot wire. The bell jar is then quickly placed over 
the basin and kept there until the phosphorus has used up 
all the oxygen, according to the equation : 

4? + 50 2 - 2P 2 5 

Phosphorus Oxygen Phosphorus Pentoxide. 

The gas remaining in the bell jar after the white clouds of 
phosphorus pentoxide have dissolved in the water is nitrogen 
mixed with argon. 

For industrial purposes all these methods are too dear, 
and the gas is manufactured from the air by the Linde 
Process already described under " Ox}^gen " in Chapter 
VIII. 

The gas obtained by any of these processes is not distin- 
guishable by our sight from ordinary air, being colourless, 
odourless, tasteless, and invisible. It is distinguished, how- 
ever, from air by a remarkable quality. It allows nothing 
to burn in it. A light plunged into it is quenched as suddenly 
as if it were plunged into water. At ordinary temperatures 
no substance appears to have any appreciable chemical action 
upon it. The element seems dead. Now note some very 
curious consequences of this. The spectroscope shows us 
that it occurs in space. All stars, all nebulae, and most 
planets contain it. In nebulas it occurs in great cloud-like 
masses, invisible to our eyes, and stretching for millions of 



THE ELEMENT NITROGEN 191 

miles through space. These dark masses of gas only acci- 
dentally, so to speak, reveal the presence of nitrogen in them 
when they gleam with the mysterious electrical fires which 
so often illuminate their exteriors. The atmospheres of 
the planets Mars and Venus are in all probability, like our 
own, composed principally of nitrogen gas ; for while oxygen 
and the other elements have for the most part been absorbed 
and combined chemically in their interiors, the nitrogen on 
account of its chemical listlessness has been left untouched 
for ages, and still blows free in the winds and breezes which 
circulate over their mountains and valleys, being in the same 
condition now as it was when these worlds were formed 
hundreds of millions of years ago. 

In order to realise more forcibly the properties of this 
element nitrogen, I wish the reader to picture the condition 
prevailing in a world whose atmosphere consisted solely of 
nitrogen gas. It is perhaps going too far to say that the 
surface of such a nitrogen planet must be a vast waste of sea, 
sand, and rock, a waste untenanted by any living thing ; 
for it is not inconceivable that forms of lif e would evolve on it 
which are capable of breathing nitrogen. Even on the earth 
at the present time many bacteria, some plants, and most 
mosses possess the capacity of slowly absorbing nitrogen. 
Under such circumstances as those we have here pictured 
this capacity could possibly develop by evolutionary means 
in a wonderful way, and on landing on such a planet we 
might find it covered with forms of life flourishing under 
conditions which would be fatal to creatures from this 
earth. 

However this may be, we may assert with certainty that 
no man or beast, if placed on the surface of the planet, could 
exist even for a minute in this atmosphere. The dead 
listless air would choke out their lives almost immediately — 
not because nitrogen is in any way poisonous in the sense 
that coal gas is, but merely because it is so chemically 
indifferent that it cannot support the combustion required 
for our lives. Men and animals require oxygen and are 
indifferent to nitrogen. 

Perhaps, however, the most extraordinary thing of all 



: 



192 MODERN CHEMISTRY 

on such a planet would be the incombustibility of every- 
thing which burns freely in the atmosphere of our earth. No 
matter how hard we tried no candle nor oil lamp could be 
lighted, and paraffin oil could be poured upon white-hot coal 
without catching fire ! Indeed, the oil would merely serve 
to quench the heat of the coal just as water would ! Our 
cheerful coal fires would be an impossibility on such a planet, 
for coal would be as incombustible as gold or stone. It would, 
in fact, be a perfectly useless mineral, and not, as on our 
earth, the source of untold wealth and power. It is true ! 
that by its destructive distillation gas could be obtained, but 
as this would be as incombustible as nitrogen itself, it too 
would be quite useless. 

Thus my readers will see that at ordinary temperatures 
nitrogen is seemingly inert and dead ; and yet this gas is 
not dead. In it are slumbering mighty forces, titanic 
energies, which await only the magic art of the chemist to 
manifest themselves in the shattering power of modern 
explosives. 

The mighty energies locked up in this gas are, indeed, 
partially liberated at high temperatures and under the 
influence of electricity. Thus, although at ordinary tem- 
peratures nothing will induce oxygen to unite with nitrogen, 
at a white heat, and in the path of a high tension discharge 
of electricity, it will unite with it so furiously that it produces 
a flame hot enough to melt, and even to boil, platinum, one of 
the most infusible of metals. When those immense electric 
discharges which constitute a lightning flash oscillate through 
the air in a mighty arc of miles in length, the nitrogen and 
oxygen in their paths are rendered white hot and combine. 
The path of a flash of lightning is thus occupied for a short 
time afterwards with a great flame of burning oxygen and 
nitrogen, and the " sulphurous smell " noticed after its near 
passage is probably due merely to oxides of nitrogen thus 
produced. 

Indeed, many elements at a high temperature possess the 
power of uniting with nitrogen, forming compounds called 
nitrides. The metals magnesium and calcium will actually 
glow if heated in the gas. The nitrides of phosphorus, silicon, 



THE ELEMENT NITROGEN 193 

boron, titanium, and wolfram are almost as stable as the 
corresponding oxides.* 

All living matter requires nitrogen. The continual restless 
movement of protoplasm, its growth and decay, is occasioned 
by this element. Indeed, without nitrogen there can be no 
life. Deprive animals or plants of food containing nitrogen 
and they sicken, fade, and die. But this nitrogen must be 
combined. Animals cannot at all, and plants can only with 
excessive slowness, absorb it when in the free state. The vast 
ocean of free nitrogen, which forms four-fifths of the air which 
blows in our faces, maintains in a chemical sense an almost 
completely listless, useless lethargy. Before the nitrogen 
can be rapidly and usefully assimilated by living matter it 
must be " fixed " by combining it with other elements. 

An account will now be given of the various modern 
attempts to solve the problem of transforming in large quan- 
tities the free and useless nitrogen of the air into the fixed 
and useful kind. This is a problem of stupendous import- 
ance to the whole human race. Solve it, and plenty and 
prosperity will smile throughout our planet. Fail to solve it, 
and there is the certainty that in a few years starvation will 
stare multitudes in the face, that hunger and want will 
stalk through all civilised lands, that revolutions will surge 
through all our towns and cities. 

This statement may seem sensational and alarming, but 
how true it is was amply proved by Sir William Crookes in 
his famous address to the British Association in 1898. f 
For every speck of living matter, even as it lives, is decom- 
posing ; and in so doing it liberates and eliminates the 
nitrogen stored up in its substance. The very condition of 
life seems change. And the atoms of nitrogen which 
occur in all living matter form the centres of instability 
from which the continual breakdown proceeds. Each 
impulse which flashes along a nerve represents the almost 
explosively rapid decomposition of a train of nitrogen 

* The reader will find a full discussion of these and allied facts 
in the author's work " Researches on the Affinities of the Elements." 

f " The Wheat Problem," by Sir W. Crookes. Chemical News 
Office, 16 Newcastle Street, London, E.C. 



194 MODERN CHEMISTRY 

compounds scattered along it. Every muscular contraction, 
every weight lifted, every movement of our body, every feeling 
of pleasure and pain, represents the decomposition of so many 
millions of molecules of nitrogen compounds. When we 
consider the countless numbers of nerves, scattered like 
complex systems of telegraphic wires through every part of 
the body, and coiled and recoiled a million times in complex 
networks in our brains, and then reflect that along each of 
these are continually speeding to and fro rapidly moving 
waves of chemical decomposition, it can be seen easily that 
the quantity of nitrogen compounds decomposed each hour in 
our bodies, and eliminated ultimately in our perspiration and 
excreta, is very considerable. This continual waste of 
nitrogen must be made good, or the animal or plant will 
sicken and die. Men and animals restore this nitrogen 
wastage by eating it in the form of animal and vegetable 
food. Every pound of meat we eat, every loaf of bread, 
represents so much combined nitrogen which passes into our 
bodies. Now the plants and the animals we eat depend ulti- 
mately upon the soil for almost every trace of nitrogen that 
they contain, and the soil in its turn has won its nitrogen 
from the air, painfully and laboriously, during the untold ages 
of the past, by vast never-ceasing cosmic processes of extreme 
slowness. The lightnings of a billion storms have combined 
it in the air ; the rains of hundreds of millions of years have 
washed it combined from the air into the soil ; billions upon 
billions of microbes in plants and in the soil have ceaselessly 
absorbed it during unnumbered ages ; consequently the 
nitrogen combined in our soil represents the united efforts 
of all Nature working continually for unthinkably vast 
periods of time. 

Even the valuable nitrogen-containing substances we 
employ in our civilisation, the rich dyes, the powerful 
medicines, the terrible explosives, are all in the same perilous 
position of depending ultimately upon the soil for their 
nitrogen. The nitrogen that we see dispersed instantly in 
the bright flash of a battleship's broadside has taken millions 
of minute organisms, laboriously working for centuries, to 
win from the atmosphere ! 



THE ELEMENT NITROGEN 195 

What do we do with the earth's precious store of nitrogen ? 
We filch it from the soil immensely faster than it is restored 
by natural processes ; and the land grows sick and barren, 
and refuses to grow our crops. Vast tracts of land, in Sicily, 
in the broad plains of Northern Africa, in the great valley 
of the Euphrates, once the richest corn-producing regions of 
the world, have within historical times grown barren and 
sterile largely owing to this cause. 

Every one knows what must be done to cure such land. 
We must impregnate it with manure or fertiliser. In other 
words, we must mix with the soil substances containing fixed 
nitrogen which the plants can utilise in building up materials 
for our food. In the olden days natural manure was sufficient 
to meet the demands of a thin population ; but in these days 
of rapidly increasing civilised man the natural manures of 
the world are far too small in quantity to be of any use. Men 
were long ago forced to the employment of artificial fertilisers. 
Indeed, there exists several sources of available nitrogen on 
the earth. For example, large amounts of nitrogen are 
obtained in the form of ammonium sulphate in the distilla- 
tion of coal in the process of gas-making. This nitrogen 
once coursed through the bodies of plants and animals which 
passed away millions of years before man trod the earth. 
After being buried for untold ages it once again sees the light 
of day, and being used for manure, finds its way into the 
bodies of plants and finally into our own bodies, so that the 
very nitrogen now in our own bodies may once have throbbed 
in the huge body of some great reptile inhabiting the swamps 
and valleys of the Mesozoic Age millions of years ago ! Little 
did such animals dream of the ultimate destiny of their 
nitrogen, as little, perhaps, as we dream of the ultimate 
destiny of ours millions of years hence ! The sober facts 
of Science are far stranger than any fairy tale. 

However this may be, the world's production of ammonium 
sulphate was in 1900 only 500,000 tons — a quantity much 
too small to meet the demands of agriculture ; nor does the 
quantity seem to be greatly extendable. There is, in fact, 
but one substance occurring in sufficient quantity to be 
used as a world-wide manure, and that is sodium nitrate 



196 MODERN CHEMISTRY 

(NaN0 3 ), or Chili saltpetre. This substance occurs native 
over a narrow band of the plain of Tamarugal in Chili. 
In this rainless district for countless ages the continual 
absorption of atmospheric nitrogen by the soil, and its 
conversion into nitrate by the slow transformations 
of billions of nitrifying organisms, has been steadily 
proceeding. * Yet even these huge supplies of combined 
nitrogen are limited. There must surely come a time, 
and that at no distant date, when these fields are ex- 
hausted. We are using up the nitrate far more rapidly 
than it is being formed. In i860, 68,000 tons of saltpetre 
were withdrawn ; in 1870, 182,000 tons ; in 1880, 225,000 
tons ; in 1890, 1,025,000 tons ; in 1900, 1,453,000 tons ; 
in 1906, it was 1,600,000 tons, and we may expect that in 
1910 something like 2,000,000 tons will be mined. Of the 
amount yielded in 1900, about one quarter passed into the 
thousands of nitrogen compounds used in our civilisation, 
the other three-quarters into food through use as manure. 
Thus, European and American agriculture is almost com- 
pletely dependent upon a tiny strip of land in a remote South- 
American Republic ; and they pay over £12,000,000 a year 
for their present import of nitrate — an oppressive and growing 
burden. Moreover, were by some internal catastrophe the 
export to cease suddenly, famine and insurrection would 
follow as surely as night follows day. 

Within thirty years these beds will be exhausted ; and 
a year or two after that famine will be upon us. 

All this was pointed out in 1898 by Sir William Crooks ; 
but he did more than point out a coming danger— he showed 
how it could be averted. His suggestions are even now being 
carried out in different parts of the world and promise to 
turn a threatened misfortune into an actual blessing, as we 
shall presently see. 

There exists in the atmosphere an almost inexhaustible 
supply of nitrogen — about 3,980 billion tons. Every square 
yard of land has about seven tons of nitrogen lying over it ; 
but all this nitrogen is " free," and therefore useless for 
manuring purposes. Combine it, or " fix " it, and plants 
can absorb it directly into their tissues. The nitrogen of 




Fig. 35. — Nodule of a Bean cut open. 

These nodules are veritable cities of nitrogen-assimilating organisms. 
Magnified about 40 diameters. Plant 4 weeks old. Photograph by Dr. 
Hutchinson, lent by Mr. John Golding, F.I.C., F.C.S., Agricultural 
College, Kingston, Derbv. 




Fig. 36.-— Nitrogen assimilating Organ- 
isms in a Bean Nodule. 

Magnified 950 diameters. Photograph 
Hutchinson, lent by Mr. John Golding 
F.C.S., Agricultural College, Kingston. 
These wonderful organisms have 
breaking down and combining 
of nitrogen of the air, therebv enriching the soil on 
which they grow. 



by Dr. 
F.I.C., 
Derby, 
the power of 
with the molecules 



- 








-1 


r 

1 










■ 1 

i 


| 












%L 






^ 


A 








T • 


■*, 


4 

f 


11 " f 

s 


jpnii 1 J 












> 



Fig. 37. — (1) No combined Nitrogen. (2) Inoculated 
with crushed nodule of a bean. 

This photograph shows very well the vigorous 
growth caused under srtiitable conditions in plants- 
impregnated with nitrogen-assimilating organisms. 
Photograph by Dr. Hutchinson, lent by Sir. John 
Golding, F.I.C., F.C.S., Agricultural College. Kings- 
ton. Derby. 

Face page 196. 



THE ELEMENT NITROGEN 197 

the air over a single square mile would, if converted into 
nitrate, be worth £25,000,000 and supply the whole world 
with enough manure to last some years ! 

Hence a method for fixing the atmospheric nitrogen 
cheaply and efficiently would be one of the greatest dis- 
coveries of Science, and recently this fixing has been done in 
more ways than one. 

Some years ago Hellriegel discovered that leguminous 
plants like clover, beans, and peas, have their roots covered 
with tiny pimples which are veritable cities of " nitrifying " 
organisms, that is to say organisms which possess the power 
of absorbing directly the free nitrogen of the air and combin- 
ing it in their tissues. Hence these organisms are continually 
performing a chemical feat which is far beyond our power. 
Silently and unceasingly, at ordinary temperatures, and with- 
out the passage of powerful electrical discharges, they are 
continually withdrawing the nitrogen of the air, com- 
bining with it and storing it up in their tissues. This 
is only another illustration of the fact of how mysterious are 
the processes going on so swiftly in the laboratory which con- 
stitutes a living cell, and how vastly superior is its chemical 
processes to those which we with infinite pain and trouble, 
using high temperatures and strong chemical reagents, 
carry out in our laboratories. Each tiny speck of living 
matter is a seething universe of atoms, rushing to and fro, 
driven by mighty unknown forces, forces emanating from 
the immeasurable ocean of intra-atomic energy incessantly 
in play within the very atoms themselves. Vitality, indeed, 
seems to be the manifestation of forces, stupendous and 
incessant, governing a world beneath the atom. No wonder 
then its chemical operations can often not be imitated by the 
crude methods of the chemist ! 

c For a long time it was thought tffat these bacteria could 
only flourish on leguminous plants, but recently Professor 
Bottomley has shown that they were not specific in their 
character and could be trained for use with other species 
of plants. Here arises a valuable possibility. By suitably 
infecting poor earths with these nitrogen absorbing bacteria 
a farmer can cause it to increase gradually its content of 



198 MODERN CHEMISTRY 

nitrogenous compounds and thus become rich and fertile 
soil. In 1896 Nobbe and Hiltner brought their microbe 
into a commercial portable form under the name " Nitragin," 
and now, after many preliminary failures, their measure of 
success has been so great that to-day several manufactories 
are perfecting their processes for the wholesale production of 
nitrifying microbes. There are hundreds of different sorts 
of these nitrifying organisms, and even now research is 
feverishly investigating them. There can be no doubt that 
by their aid we can restore to the soil the fertilising nitrogen 
which in the past we have so extravagantly wasted. Indeed, 
we are here merely imitating Nature, hastening her slow 
processes to meet our wants.* This process of imitation 
is now being carried out in still another direction, and, per- 
haps, with even greater success. 

We have seen that the lightning flash burns the air in its 
path into oxides of nitrogen, which, when washed down by 
the rain into the soil, quickly become fixed as nitrates. Not 
only lightning, but also the silent electric discharges which 
are always taking place in the atmosphere cause the oxygen 
of the air to combine with the nitrogen to form nitrites and 
ammoniacal salts. Something like 400 million tons of com- 
bined nitrogen thus fall every year into the earth or sea as 
the result of this electrical action, f or more than a thousand 
times more than is at present artificially supplied by Chili 
saltpetre, which in 1905 amounted to 260,000 tons of 
combined nitrogen. 

Lightning is but a vast electric spark ; hence by flashing 
through the air electric sparks we can cause the air to burn 
and produce nitric acid and nitrates. So long ago as 1892 
Sir William Crooks exhibited at one of the Soirees of the 
Royal Society an experiment on " The Flame of Burning 
Nitrogen." By passing a strong induction current between 

A 

* For further information the reader should see " The World's 
Work," Sept., 1907, p. 372. Reference may also be made to the 
valuable papers of Mr. John Golding, F.I.C., F.C.S. His Presidential 
Address, "Adaptation," to the Nottingham Naturalists' Society, 
1907-8, gives a complete account of the question. 

f Arrhenius, " Das Werden der Welten," p. 130 (190S). 




-The Works at Notodden, where fertilising nitrates are produced 
from the atmosphere. 




39. — Lightning. 

w A l th °"t gh ** soraet .™ es causes disaster, lightning is of great value to all living things 
tLL^L? e T ? l H 0f iZ n l et l m v to the soil in a form suitable for assimilation by plants! 
S^^ m + enSe - heat ? f the flash burns U P the air ^ its path, causing the ox/gen and 
nitrogen to unite to form nitrates and nitrites which are washed down by the downpour] n 

l*v t^^' M ^- e ? an 4 °° miUion tons of nitro § en are combined ySS 
X thSin t£s e w C a™ ^ mtr ° gen * the "* ^ ta Kving thhl & haS beeQ ob ^ ined 

Face page 198. 



THE ELEMENT NITROGEN 199 

terminals he showed that the air took fire and continued to 
burn with a powerful flame, producing nitrous and nitric 
acids. With truly prophetic words he said,* " This incon- 
siderable experiment may not unlikely lead to the develop- 
ment of a mighty industry destined to solve the great food 
problem/' How his words have been fulfilled will be seen in 
the sequel. 

The first successful nitrate factory was set up by Professor 
Birkeland and Dr. Eyde at Notodden in Norway. Here 
amid all the magnificent scenery of the land of hills and 
dales, by the still waters of a lake which provides water 
carriage all the way to Christiania and Hamburg, and on the 
banks of a rushing torrent of water which supplies abundant 
power to drive the great dynamos which generate the electric 
current, may be seen a little group of houses, the nucleus, 
perhaps, of a great manufacturing town of the future, where 
the fertilising nitrates are directly produced from the atmo- 
sphere. A rough diagram of the apparatus is shown in 
Fig. 41. By means of a powerful alternating current of 
3000-5000 volts a powerful electric arc is formed between two 
copper electrodes placed in a stream of air. The electrodes are 
hollow and are traversed by a stream of cold water to prevent 
them fusing in the heat produced. The terminals of the 
electrodes are placed at a distance of eight mm. to one cm. 
apart, or between one-third and one-half inch apart. The arc 
is deflected at right angles to the direction of the electrode by 
means of a powerful electro-magnet placed in such a way that 
the terminals of the copper electrodes are in the middle of 
the magnetic fields as shown in Figs. 48 and 49. Instantly a 
great roaring rotating disc of immensely hot flame of 
burning nitrogen gas, six feet in diameter, forms between the 
electrodes. The gases from the flame are pumped off. They 
contain two-thirds per cent, of nitric oxide (NO) formed thus : 

N 2 + 2 = 2NO 

Nitrogen Oxygen Nitric Oxide. 

ine gases are cooled down gradually and the nitric oxide 
is converted into nitrogen peroxide by allowing it to mix with 

* Presidential Address to the British Association, 1898. 



200 MODERN CHEMISTRY 

air in a reaction tank of sheet iron enamelled on its inner 
surface. The equation is : — 

2NO + 2 = 2N0 2 

Nitric Oxide Oxygen Nitrogen Peroxide. 

From this reaction tank the nitrous gases pass through 
dripping nitric acid and up water towers, where they meet 
with dilute caustic soda or milk of lime. A mixture of sodium 
or calcium nitrate and nitrite is then formed, according to 
the equations : — 

2N0 2 + H 2 = HNO3 -f HN0 2 

Nitrogen Water Nitric Acid Nitrous Acid. 

Peroxide 

HNO3 + HN0 2 + 2NaOH = NaN0 3 + NaN0 2 + H 2 

Nitric Nitrous Caustic Sodium Sodium Water. 

Acid Acid Soda Nitrate Nitrite 

2HNO3 + 2HN0 2 + 2 Ca(OH) 2 = 

Nitric Nitrous Milk of 

Acid Acid Lime 

Ca(N0 3 ) 2 + Ca(N0 2 ) 2 + 2 H 2 

Calcium Calcium Water. 

Nitrate Nitrite 

The mixture of calcium nitrate and nitrite can be used 
directly as a manure. 

In practice the alternating current disc-flame is enclosed 
in a special furnace lined with fire brick and furnished with a 
metal casing. The fire chamber of the furnace is narrow 
■ — from five to fifteen cms. wide — made partly of perforated 
chamotte, air being conveyed to the disc-flame, in an evenly 
distributed supply, through its walls. The air is driven at 
the rate of 3,000 feet per minute into the central region on both 
sides of the flame by gentle pressure from a Root's blower ; 
and after passing in a radial direction arrives at a peripheral 
channel, whence it is conducted away. This process is still 
limited in extent, because sodium nitrite from Chili is still so 
cheap. When, however, the nitrate fields become exhausted, 
and at the same time the population of the world has greatly 
increased, the method will probably grow enormously in 




w 



PQ 



CM 

o 

i-; 

c 






THE ELEMENT NITROGEN 



201 



value and may later become a vast industry employing 
thousands of workmen all over the world.* 

Another process for fixing atmospheric nitrogen, entirely 
different in principle from the foregoing, has been intro- 
duced by Prof. Franke of Charlottenburg. He found that 
when atmospheric nitrogen is passed over red-hot calcium 




Fig. 41. — Diagram illustrating the Principle of the Birkeland-Eyde 
Electric Furnace. A powerful alternating current of 3,000 to 5,000 
volts is sent through the electrodes a and b, which consist of copper 
tubing, through which a rapid stream of water is kept circulating in 
order to prevent them from fusing in the intense heat of the electric 
arc generated between them. A powerful electro-magnet placed as 
seen in the diagram blows out the arc into a rotating disc of flame, 
which in appearance looks something like a " Catherine Wheel," and 
consists of burning nitrogen and oxygen. 



* For further details of this process, see the Electrician, July 13, 
1906, p. 494. Also " The World's Work," Vol. X., p. 493, 1907. 



202 MODERN CHEMISTRY 

carbide it is absorbed and calcium cyanamide is formed, 
thus : — 

CaC 2 + N t CaCN 2 J- C 

Calcium Carbide Nitrogen Calcium Cyanamide Carbon. 

This body may be considered as a derivative of ammonia, 
being the calcium salt of cyanamide : — 

NH3 NH 2 ~CN Ca=N-CN 

Ammonia Cyanamide Calcium Cyanamide. 

When this calcium cyanamide is heated with water under 
pressure, ammonia is set free according to the equation : — 

CaCN 2 + 3H 2 = CaC0 3 + 2NH3 

Calcium Cyauamide Water Calcium Carbonate Ammonia. 

or Chalk 

Next it was found that this substance when merely spread 
over the soil was slowly decomposed by the moisture, yielding 
ammonia and chalk or limestone, and consequently could be 
used directly as a fertiliser. Indeed, it is stated that the 
substance is a better fertiliser than ammonium sulphate from 
gas works, and is quite as good as the best saltpetre. Under 
the name " Kalkstickstoff " or " Nitrolime " it is now on the 
markets of the world. 

A very interesting property of cyanamide (which can be 
obtained from calcium cyanamide) is the ease with which 
it unites with water to form urea — the substance occurring 
in urine. 

CN— NH 2 + H 2 - CO(NH 2 ) 2 

Cyanamide Water Urea. 

Tons of this artificial urea are now made and sold to 
manufacturers of pharmaceutical preparations. Guanidine, 
another product of the animal body of which tons 
are now sold, can also be made from it. Still more wonderful, 
one of the actual substances — creatine — found in human 
muscle, and forming the stimulating principle of beef tea, 
can actually be prepared by uniting sarcosine with cyana- 
mide ! Perhaps we may look forward to the time when 
many of the actual constituents of our food are directly manu- 
factured from atmospheric nitrogen ! We may still live 



THE ELEMENT NITROGEN 203 

to see the creation of as many factories for fixing atmos- 
pheric nitrogen as now exist for smelting iron.* 

All these facts teach us that the idea with which we 
started this chapter, namely, that nitrogen is a dead, inert 
element, is not altogether correct. Inert it certainly is, 
when compared to most other elements. Yet, like oxygen, 
the other constituent of our atmosphere, it is continually 
taking part in a vast cycle of cosmical change by means of 
which life is maintained upon this earth. According to 
Arrhenius nitrogen takes part in the vegetative processes 
nearly a hundred times less rapidly than oxygen, and yet, 
so vast is the scale on which the fixation of nitrogen is 
going forward in Nature, no less than one part out of every 
three million of atmospheric nitrogen is annually removed 
from the air and conveyed to the soil by the incessant 
electric discharges which are going on everywhere over land 
and sea.f 

Now the world is hundreds of millions of years old, and if 
these processes have been going on for all this time the 
reader will naturally wonder why there still exists any nitro- 
gen in the air. At this rate of fixation a few million years 
would have sufficed to completely deprive the atmosphere 
of nitrogen. And yet we find when we examine the crust of 
the earth that nowhere is there a tendency of nitrogen to 
accumulate in it. The quantity now fixed in the soil is 
only just sufficient to supply the wants of the vegetative 
world. It is clear therefore that there must be some process 
at work which gives back to the air the nitrogen which 
yearly is taken from it. And this is so. When animals 
and plants die and their bodies decay, a considerable propor- 
tion of the bound nitrogen in them is set free again by 
bacterial activity and by oxidation, and finds its way back to 
its original home, the air. Many of the complex nitrogen 

* For further details the reader should see " The Electrochemical 
Problem of the Fixation of Nitrogen," by Prof. Philippe A. Guye, 
Journal of Chemical Industry, June 30, 1906. Also " Chemical 
Industry in Relation to Agriculture," by Prof. Franke, Journal 
of Chemical Industry, November 30, 1908. Vol. 27, 1904. 

f Arrhenius, "Das Werden der Welten," pp. 130, 131 (1908). 



204 MODERN CHEMISTRY 

compounds in their bodies, however, pass directly into the soil 
and thence are absorbed by the roots of plants. Now all 
animals obtain their nitrogen by devouring plants, and these 
indirectly or directly obtain their nitrogen from the air. 
Consequently there is continually going on in Nature an 
immense and endless circulation of nitrogen. Stupendous 
quantities are every year withdrawn from the air, and 
stupendous quantities are returned to it each year. No 
less than 400 million tons pass in and out of the atmo- 
sphere in this way as compared to 40,000 million tons of 
oxygen ! 

Every scrap of nitrogen in our bodies once floated in the 
primeval atmosphere ages before man or beast or plant arose. 
Every particle of nitrogen in every living thing that creeps 
upon the earth, in every flower that nestles on the ground, 
in every tree that grows aloft to heaven, once streamed in 
the primeval winds of our planet. There is no atom of 
nitrogen in the air that has not at some time or other in the 
course of its existence throbbed through the tissues of a 
living plant or animal, not once but many times. 

What a wonderful story, to be sure, could be written of 
the journeyings of any one of the nitrogen atoms in our own 
bodies ; how it started its existence in the silent black depths 
of space thousands of millions of years ago ; how it then went 
to form part of the great fiery nebula from which the world 
condensed ; how it then j oined the primeval atmosphere of 
the world, until some mighty flash of lightning in some 
forgotten storm hundreds of millions of years ago smote it 
suddenly, and combined it with oxygen ; then streaming 
rain of a thunderstorm washed it down into the soil. 
How it then entered the rootlet of some plant, and passed 
into its body, and thence, in the course of endless time, into 
the bodies of a vast series of creatures who lived and fought 
and died ages before we came into existence. It has coursed 
through huge reptiles wallowing in the mud of long-vanished 
swamps, through extinct plants, through insects, bacteria, 
and an endless array of other living things, until at last it 
entered our bodies combined in the food we eat. After a 
few years or, perhaps, months' sojourn there it will leave us 



THE ELEMENT NITROGEN 205 

and again continue its wanderings in the bodies of plants and 
animals and even in the atmosphere again. 

Millions of years after man and all his works have passed 
like a dream from the earth, the nitrogen atoms which once 
thrilled in his body will still vibrate in other living forms of 
life, forms perhaps unknown and undreamt of by him. 
Truly, when we contemplate Nature closely we find her always 
in a state of change, stupendous and never-ceasing, and we 
realise how true and deep were the words of that old-world 
thinker, Heraclitus, who twenty-five centuries ago declared, 
r Change is everywhere ; everything is and is not. There 
is no stability. Even in the same river one cannot bathe 
twice, nor even once." 



CHAPTER X 

THE ELEMENT CARBON 

The element carbon is, directly or indirectly, the source of 
nearly all the power used at the present day in the civilised 
world. The hundreds of thousands of great steam engines 
ceaselessly working night and day at the present time through- 
out the whole earth, driving whirling machinery for all the 
manifold purposes of a great and complex civilisation, 
derive their gigantic energy from the use of this element as 
a fuel in the form of coal. The mighty furnaces scattered 
in countless numbers over every civilised land, whose red 
tongues of flame waving above their fiery throats light up 
the sky with a lurid glow in all our great industrial centres, 
are fed by it. The steel of pen and sword and gun, of engine, 
girder, rail and bridge, are obtained by its means. Without 
abundant and cheap supplies of it such valuable and neces- 
sary products as copper, iron, tin, lead, and porcelain 
would scarcely be known except as expensive chemical 
curiosities. Indeed, our whole present-day civilisation may 
truly be said to rest upon the use of carbon as a fuel. With- 
draw it suddenly from use and all industry would be para- 
lysed. The great factories would close down through lack 
of power, turning adrift the thousands of men and women 
employed in them. Engines would cease to run from town 
to town, and steamers to ply their busy trade on sea and river. 
Great liners would roll helplessly at anchor in all our seaports, 
unable to venture out to sea. All the arteries of commerce 
would be choked and stopped, and ruin would fall upon us 
all. At first sight it is altogether hard to realise how inti- 
mately coal is woven into the life of civilised man ! In our 
homes carbon provides us with warmth during the cold 
winter months, and in its absence most of us would probably 

206 



THE ELEMENT CARBON 207 

have to eat our meat raw as did our forefathers ages ago. 
In the form of a costly gem, as diamond, carbon gleams 
on the breast or in the hair of many a whirling ball-room 
beauty, while as graphite or plumbago it not only provides 
us with blacklead pencils, but also serves for polishing our 
boots and for lubricating machinery. Besides being one of 
the most useful elements, carbon is also one of the most widely 
distributed. It occurs free in the earth as coal to the extent 
of over 500 billion tons, while chemically combined it is 
found in far larger quantities in limestone, chalk, marble, 
and dolomite, rocks which form so considerable a portion of 
the surface of our planet. In every 100 tons of marble 
are nearly twelve tons of coal or carbon, and a slightly smaller 
quantity exists in the same weight of the other rocks just 
mentioned. When we reflect that vast mountain ranges, 
and giant plains, extending for thousands of square miles 
in area, and for thousands of feet in thickness, are composed 
of these rocks, we can easily imagine that the amount of 
carbon thus stored up is stupendous. Once combined, 
however, we cannot extract the carbon again economically, 
and, regarded as a possible fuel, this carbon is irretrievably 
lost. 

It is a matter of common knowledge that all living matter, 
whether of animal or of vegetable origin, when heated strongly 
in the absence of air, chars and turns into a mass of black 
coke, thus showing that the element is an essential constitu- 
ent of all living matter. According to Pettenkofer a man 
weighing seventy kilos (154 lbs.) contains twelve kilos 
(26.4 lbs.) of carbon or charcoal ; no less than 257 million tons 
weight of it are stored up in the bodies of men and women 
living upon the earth at the present time, to say nothing of 
the far greater quantities occurring in the tissues of trees, 
plants, and animals. Indeed, coal itself is merely the fos- 
silised carbon of an old-world vegetation which flourished 
millions of years ago. 

Carbon is not confined to this earth alone. It is scattered 
in inconceivably vast quantities throughout space. Every 
tiny meteor flying swiftly and silently through space, 
every grain of cosmic dust, every comet, every planet 



208 MODERN CHEMISTRY 

whirling round its central sun, nay, every one of the thou- 
sands of millions of suns scattered through space contain it. 
In our own sun it occurs as a gas which condenses in the 
upper regions of its atmosphere to huge clouds of soot, 
thousands of miles in diameter and billions of tons in weight, 
soot not black like the soot from our chimneys, but glowing 
with an intense heat, and emitting a blinding, dazzling light. 
These soot clouds surround the sun with a fiery mantle, 
much as clouds surround our earth, and to them is due much 
of the fierce brilliance of his surface. 

The three distinct forms in which the element carbon 
occurs, namely : diamond, graphite, and amorphous carbon 
or charcoal, differ so greatly in properties that we will 
consider each modification separately. 

Chemistry proves beyond all doubt that the exquisitely 
beautiful thing that we call a diamond* and a piece of ordinary 
coal or charcoal are composed of the same substance — carbon. 
The diamond is only carbon which has been fused at an 
enormous temperature and pressure and then allowed to 
slowly crystallise. This may be proved in many ways. In 
the first place we can turn charcoal into diamond, and con- 
versely we can by intense heating turn diamond into char- 
coal. Again, we can burn both charcoal and diamond in 
oxygen gas, and in each case we get the same gas, carbon 
dioxide, produced, and the same weight of it too when we 
start from equal weights of diamond and charcoal. 

Some years ago a ring of speculators ran up the price of coal 
to fifty shillings a ton, and a picture appeared in Punch of 
a gentleman wearing a coal scarf-pin, which he proudly 
declared to be " real Wallsend." Many a true word is 
spoken in jest, for, chemically, a bit of Wallsend is of the 

* For further information on this interesting subject the reader 
should read Sir William Crookes on " Diamonds," Chemical News, 
October 6, 1905, Vol. 92, p. 159. Popular articles have appeared 
recently in The Pall Mall Magazine, Vol. 20, p. 182 (1900), in an 
article entitled " Gems," by T. C. Hep worth, and in The English 
Illustrated Magazine, Vol. 20 (1899), p. 647. Also " Artificial Dia- 
monds " in Knowledge, February, 1908, Vol. 5, p. 26. In Streeter's 
" Precious Stones " a valuable and interesting account of the 
subject will be found. 



THE ELEMENT CARBON 209 

same value as an equal weight of diamond. And yet what 
an enormous difference exists between them in price ! A 
ton of the best coal may cost twenty shillings, but a ton of 
good diamonds would be worth about eight million pounds. 
Yet possibly in future the intrinsic value of the two will 
more nearly approximate, for diamonds can now be made 
in the laboratory, as we shall explain immediately, although 
at present the cost of the operation is greater than the value 
of the gems produced. Still, who can tell what improvements 
in the process may be made in the future ? 

Until recently carbon was considered to be quite involatile 
and infusible. We now know, however, that it volatilises 
at the enormous temperature of 3,600° C. without melting. 
The reason of this is that its boiling point under atmos- 
pheric pressure lies below its melting point ; in other words, 
it boils before it melts. Arsenic is the only other element 
which does this. Now we have seen in our chapter on water 
that the greater the pressure we apply to a substance the 
higher the temperature at which it boils. For example, 
water boils at ioo° C. under atmospheric pressure, but when 
we increase the pressure on its surface to 196 atmospheres 
it then boils at 370° C. — a low red heat. In the same way by 
subjecting carbon to a pressure great enough we could raise 
its boiling point without affecting its melting point much, 
and thus we could cause it to boil above its melting point. 
We should thus possess the power of melting carbon and of 
making diamonds artificially by allowing the molten liquid 
to slowly cool and crystallise. 

Sir William Crookes calculates that at a temperature of 
about 4,130° C. a pressure of only seventeen atmospheres 
would liquefy it. There can be no doubt that by subjecting 
carbon to a very great pressure and an enormously high 
temperature (lower than 5,500° C. — its critical temperature, 
— and higher than 4,130° C, its melting point) we should 
transform it into a clear colourless liquid. On allowing this 
liquid to cool very slowly the carbon would crystallise out 
as large transparent sparkling diamonds. 

Chemists have not yet succeeded in performing this experi- 
ment on a large scale ; but a great French chemist — Moissan 




210 MODERN CHEMISTRY 

— actually succeeded in making microscopical diamonds 
in this way.* 

This was done as follows: Iron when melted dissolves 
carbon much as water dissolves sugar, and on cooling at 
ordinary pressures liberates it in the form of graphite. 
Moissan now asked himself the question : Will the carbon 
separate out as diamond if the pressure be enormously 
increased ? To test this he compressed pure charcoal (made 
by charring sugar) into a cylinder of soft iron, closed it 
with a plug of the same metal, packed it with charcoal into 
a carbon crucible and heated the whole for a few minutes 
in an electric arc to the enormous temperature of 4,000° C. 
— a temperature at which iron melts like wax and volatilises 
in clouds — and plunged the dazzling fiery mass beneath 
cold water in order to cool it suddenly. We can well imagine 
that the great experimenter, as he himself confesses, carried 
out this portion of the experiment with a considerable degree 
of nervousness, half expecting that a violent explosion would 
be the result. For molten iron when plunged into water 
has been known to explode disastrously owing to the genera- 
tion of gas. Indeed, so hot was the iron that it remained 
red hot in the boiling water for some minutes. Luckily all 
went well. The iron cooled and solidified to a hard mass of 
steel on the outside. Now iron increases in volume when 
passing from a liquid to a solid state. The sudden cooling 
solidified the outer layer of iron and enclosed the inner molten 
mass with a rigid, immensely strong envelope. The inner 
liquid iron then solidified and expanded in so doing against 
the rigid enclosing envelope. An enormous internal pressure 
was thus produced and under stress of this pressure the 
dissolved carbon separated out as diamonds — not large dia- 
monds such as you see in a jeweller's window, but small, 
sometimes microscopical ones, worthless as gems, but all 
the same real diamonds, answering to all the physical and 
optical tests of the native ones dug out of the soil. These 

* The first artificial diamonds were made by Hannay and Hogarth 
in i860. Improvements in the process were introduced by Luzi, 
Moissan, and Majosana, but even at the present time (1909) they have 
not been manufactured on the large scale- 



THE ELEMENT CARBON 211 

diamonds, however, are imbedded in a mass of steel and gra- 
phite. To separate them the iron was dissolved away in 
strong acids, and there remained behind a mass of graphite, 
which, when repeatedly boiled in a mixture of sulphuric 
acid, nitric acid, and powdered potassium chlorate, gradually 
oxidised away and left behind the tiny diamond. 

The largest artificial diamond yet produced measures less 

than one millimetre across (say -^ part of an inch) and so is 

valueless. Still the problem of making larger diamonds is 

chiefly a matter of power and pressure and length of heating. 

When we can deal with a thousand pounds of iron as easily 

as we now deal with four or five ounces, then doubtless 

large diamonds will be produced. Nature in the depths of 

the earth operates with gleaming furnaces hotter than any 

that we can produce, with vast pressures due to hundreds of 

miles of overlying rock and earth, with time reckoned in 

thousands of years, and with quantities reckoned in millions 

of tons ; as a result of these titanic operations she produces 

j magnificent diamonds such as at present we can only admire, 

not imitate ; but who can sa} what the future holds in her 

lap ? Perhaps our children \\ ill yet hold in their hands as 

playthings artificial diamonds mch as would now be worth 

millions and be deemed worth 7 to glorify crown or sceptre ! 

We have reason to believe diat diamonds are formed in 

; Nature by a process somewh; t similar to that followed by 

1 Moissan in his experiments. Deep down, buried beneath 

: some six hundred miles of molten or white-hot rock, there 

- lie vast masses of iron and other metals heated to a tempera- 
ture enormously higher than that which we can produce in 

s our laboratories. Hundreds of miles of rock lying above 
it have compressed this iron with a force so stupendous as 
to be almost inconceivable to us, while at the same time it 
is impregnated with carbon, which under such conditions 

- is freely miscible in it. In consequence of slow upheaval 
going on for ages, and sometimes on account of some great 
volcanic disturbance, these low-lying carbonaceous layers are 
sometimes forced nearer the surface, and then slowly cool 
during hundreds or thousands of years. In consequence of 
this the dissolved carbon separates out fs tiny fluid globules, 



2ia MODERN CHEMISTRY 

which run together and form still larger globules. Finally 
as the magma cools down still more, the carbon crystallises 
out as diamonds. The general appearance of many of these 
precious stones favours this view of their origin. Some 
diamonds look like drops of liquid which have separated 
in a pasty condition and have then crystallised on cooling. 
Others have but little appearance of crystallisation, but 
have a round form, similar to that assumed by a liquid 
when kept in the midst of another with which it will not 
mix. If many of these drops of liquid carbon are maintained 
for a sufficient time above their melting points they coalesce 
with adjacent drops, and on slow cooling separate out in the 
form of large perfect crystals. Diamond crystals are gener- 
ally perfect on all sides. They show no irregular side or 
face by which they were attached to a support — another 
proof that they have crystallised out from a dense liquid. 
The extreme internal tension known to exist in diamonds 
which causes many to burst or explode when brought to 
the surface for the first time indicates that they have been 
formed under conditions of great pressure deep down in 
the earth, a pressure from which they relieve themselves 
when they suddenly expand outwards and fly to pieces. 
Most artificial diamonds and many natural ones are but 
fragments or splinters of perfect crystals, which have burst 
in this way. 

Undoubtedly the diamonds now found near the surface of 
the earth have been brought up from the earth's molten 
interior by the volcanic convulsions of former ages. At 
any rate in South Africa the diamonds are actually found in 
old volcanic ducts rilled with a peculiar blue earth which, 
like vast " pipes " or " chimneys," ri e from unknown 
depths and burst through the surrounding shales. The 
old volcanoes, of which these were the throats, have, however, 
been swept away ages ago by wind and rain from off the 
earth, and their materials disseminated over the surrounding 
districts. All that remains of them are these pipes plunging 
into the earth. The diamonds that we find so often in the 
beds of streams, and in alluvial soils, occur in the debris 
of these washed awav volcanoes. The diamond is chemically 




:; & 




J ' 1 ?* 






If 



r- 



m« 



riii n" : 'nil'" ' ■ 



— 



THE ELEMENT CARBON 213 

almost unalterable at ordinary temperatures and endures 
for ages. Long after the rock in which they were originally 
imbedded has been corroded away by wind, rain, and car- 
bonic acid, the diamond remains unchanged. The vast 
diamond fields of old India were of this alluvial nature and 
are now exhausted ; but somewhere under the soil, perhaps 
buried by the mud and ash of millions of years, there still 
must exist old diamond pipes coming out from the depths 
below. No man has found them yet, and perhaps we 
never shall ; but deep down the diamonds are still there, and 
may some day be discovered by a lucky adventurer. 

In South Africa, however, these pipes have been discovered, 
and the miners are steadily digging their way down them 
towards the interior of the earth. Already they have pene- 
trated them for thousands of feet, and still there is no diminu- 
tion or slackening in the diamond supply. How far down 
these mines will ultimately extend we cannot say. The 
heat of the earth will prevent them from going deeper than 
a few miles, but there is no reason to doubt that the 
diamond rich pipes may go down for scores of miles into 
white hot regions below, and join immense reservoirs of 
diamond-rich rock. s 

The discovery of these diamond fields is itself a romance. 
It appears that in 1867 a child of a Dutch farmer, Jacobs 
by name, found a pretty pebble in a stream in the neighbour- 
hood of the farm, near Hopetown. The brightness of the 
stone attracted the keen eye of the mother, though she 
regarded it simply as a curious pebble, and gave it little more 
than a passing glance ; but in the solitude of the bleak 
countryside every little incident furnishes food for conversa- 
tion, and so it happened that some time afterwards when a 
neighbouring boer, named Schalk van Niekerk, visited the 
farm, Mrs. Jacobs told him about the bright transparent 
stone. Being a thoughtful intelligent man, interested in 
such things, he asked to see it ; yet so carelessly had the 
stone been kept that when wanted it was nowhere to be seen. 
After 'some searching it was at last found lying on the ground 
just outside the house, where it had happened to fall when 
the child had used it last as a plaything. Van Niekerk 



214 MODERN CHEMISTRY 

had never seen a stone like this before and offered to buy it. 
Mrs. Jacobs laughed at the notion of selling so common a 
pebble, and at once gave it to the farmer. The latter put 
it in his pocket and some time later showed it to a trader, 
O'Reilly by name, who was going south from a hunting and 
trading expedition, and asked him to try to ascertain its 
nature from any trustworthy mineralogist he might meet. 
It was taken to Colesburg and thence dispatched by post 
to Dr. Atherstone, of Grahamstown, who was known to be 
an excellent mineralogist. Of so little value was the stone 
thought to be that it was sent unregistered through the post 
gummed up in an envelope as an ordinary letter. Dr. 
Atherstone after a careful examination pronounced it to 
be a diamond. And so it happened that the plaything of 
a child was sold later for £500 ! 

Of course this discovery caused a great sensation, and every 
one began searching their back gardens for diamonds, with 
the result that these stones were found scattered far and wide 
over the whole countryside. 

Near Colesburg a Dutch farmer named Tan Wyk was 
surprised to find diamonds actually imbedded in the walls 
of his house, which had been built of mud from a neighbour- 
ing pond. This led to the ground round about being exam- 
ined, which was also found to contain diamonds. Soon a 
rush of men occurred to the place, and it was found that on 
continuing to dig lower and lower diamonds were still brought 
to light ; nor did they cease when the rock bed was reached. 
Such was the origin of the famous Kimberley Diamond 
Mine, which from that day to this has never ceased working, 
and which at the present time employs nearly twelve thousand 
coloured men and three thousand white men. Over ten 
tons weight of diamonds have been found, representing a 
value of about eighty million pounds. So long ago as 1899 
the company were exporting over two million pounds worth of 
diamonds, and since that date the quantities have increased. 
Indeed, experts say that the mines are inexhaustible. The 
work goes on night and day, Sundays included, without 
intermission. Two thousand men are employed below for 
eight hours at a time. The remainder live on the surface, 



THE ELEMENT CARBON 215 

and while awaiting their turn are enclosed in compounds, 
vast squares walled in and surrounded on the inside with 
sheds, where the negroes sleep on the bare ground. " They 
are entirely cut off from the outer world for three months," 
says Mr. Sillard,* " then, any one who wishes to leave his 
work (except the convicts) is kept in a room by himself for 
a week, where all his clothing is taken from him, and he is 
compelled to take medicine of no delicate nature, lest he 
may have swallowed some of the coveted gems. That such 
precautions are necessary can be gathered from the fact that 
some time ago one fellow had a sore leg, and had it well 
bandaged just as he was leaving. The defective limb was 
examined, and in a self-inflicted wound were found nine small 
diamonds, worth about sixty pounds." 

Sometimes visitors are allowed down the mines, and it is 
a sight never to be forgotten. " They are," says Mr. Sillard, 
" first provided with a full rig-out of waterproof clothing, 
boots, and other apparel. They are then brought to the 
hauling gear, and put into a cage-like lift, or elevator, which 
descends at a very rapid rate through intense darkness 
for a distance of fifteen hundred feet or more. When the 
visitors are ' landed ' they find themselves in a vast chamber 
brilliantly illuminated with electric lights, and a thousand 
coloured men at the searching work. They are next con- 
ducted through a tunnel half a mile long to where the diamond 
bearing material is being dug up. Along this tunnel are 
two lines of rails with many hundreds of trolleys ; one set 
of rails conveying full, and the other empty trolleys, and all 
propelled by the same endless wire cable. The ' blue 
ground ' which bears the diamonds is brought to the surface 
in astonishing quantities. It is spread on floors, about five 
hundred acres in extent, or several months. Here it 
disintegrates to dust and then the precious gems are col- 
lected. All round these floors are placed guards at short 
distances, who keep watch day and night, and on an emin- 
ence is a sort of observatory furnished with powerful tele- 
scopes, searchlights, etc., so that even on the darkest night 
any part of the floors, or any of the guards or workmen, can 

* The English Illustrated Magazine, Vol. 20, March, 1899, p. 651, 



2i6 MODERN CHEMISTRY 

be inspected instantly. It may be gathered from this short 
sketch that there are few places of more interest on our 
planet than a Kimberley diamond mine." 

Next time my reader sees a diamond gleaming in a jewel- 
ler's window in a busy city street, or glittering on a lady's 
attire amidst the light and music of a ballroom, let him 
recollect for a moment its strange story ; how it was conceived 
in the depths of the earth in an ocean of liquid fire ; how it 
slowly grew and took form during countless ages of slow 
cooling in mighty subterranean furnaces ; how it was sud- 
denly brought to the surface during some titanic convulsion 
of the earth's crust, when, amidst vast thunderings, the earth 
split open and torrents of white-hot molten rock came pour- 
ing out from the throat of some old-world long-vanished 
volcano, millions upon millions of years ago, bearing with it 
our diamond; how it lay buried in rock in utter silence 
and darkness for age after age, while successive races of plants, 
animals, and men, came into existence, rose to power, 
slowly declined and passed away ; how then at last its long rest 
was broken, the pick axe of man was heard, daylight flashed 
in upon it, and it was plucked from its age-long hiding-place, 
and sent to circulate from hand to hand in the world of men 
and women. Whence came the carbon of the diamond ? 
Probably from a living plant. Yes, possibly every diamond 
in the world at some remote epoch, millions upon millions 
of years ago, formed part of a living plant ! First as carbon 
dioxide gas in the air, then as wood in a tree, then as coal, 
then, deeper in the earth as graphite, and finally, after under- 
going the purification of the fierce central fires, as a glittering 
gem — this is the strange life-story of the diamond ! 

The diamond is the hardest of all known substances. So 
hard is it in comparison to glass that a suitable diamond 
splinter will plane curls off a glass plate much as a carpenter's 
tool planes shavings off a wooden board ! Although so 
hard it is very brittle. A fall may smash it like a piece of 
glass, while a blow from a hammer will shiver it into dust. 

When first found diamonds are rough, unattractive pebbles, 
and it is only after they have been cut and polished that 
they become the beautiful gems we see set in rings and tiaras. 




pq 



o3 

H 

to 

a 

o 

l-l 
oi 
o> 
CD 



THE ELEMENT CARBON 217 

We have already alluded to the fact that many diamonds 
are in a state of intense internal stress or strain. Some of 
them contain millions of minute cavities filled with gas at 
enormous pressure. Liquid carbon dioxide is often contained 
in them, and the strain is set up in the stone by the effort 
of the gas to escape. This is the reason why diamonds so 
often explode soon after reaching the surface of the earth. 
Some have been known to burst in the pockets of the miners 
or when held in the warm hand. The loss is often very 
considerable, as large stones are more liable to fly to pieces 
than small ones. 

It is said that dishonest dealers often allow responsible 
clients to handle or carry in their warm pockets large crystals 
fresh from the mines. To insure against explosion when 
transmitting diamonds long distances many dealers embed 
them in raw potatoes. A very fine piece of artificial diamond, 
carefully mounted by Sir William Crookes on a microscopical 
slide, exploded during the night and covered its slide with 
fragments. This phenomenon appears to be the reason 
why in Nature so many diamonds appear as splinters broken 
off from larger crystals. The same thing applies to the arti- 
ficial diamonds. It is only very seldom that a perfect crystal 
is found. 

Since the diamond is only crystallised coal it is but natural 
that it will burn. Indeed, it would be possible to have 
under certain conditions a diamond fire instead of a coal 
one, although, I am afraid, that this would be an expensive 
luxury even for a millionaire. He would have to pay about 
eight million pounds for every ton of diamonds he burnt. 

If a diamond be heated white hot and plunged into a jar 
of oxygen gas it will burn with a dazzling white light, just 
like a bit of coal or charcoal would under the same circum- 
stances, leaving behind a minute trace of ash and forming 
the invisible gas carbon dioxide : 

c + o 2 = co 2 

Diamond Oxygen Carbon Dioxide. 

It is almost unnecessary to say that this is the gas yielded 
by every fire and gas burner, and by the combustion of 



218 MODERN CHEMISTRY 

our own bodies. These latter, in the combustion that attends 
their very living, evolve carbon dioxide by the lungs, so 
" that the old fable of the maiden from whose lips fell 
diamonds may have a really scientific basis after all." 

It is related that owing to this cause Francis I. of Austria 
in 175 1 suffered a great loss. The story runs that one 
morning he received an anonymous letter from an alchemist 
containing full directions for melting diamonds. The king 
at once placed together in a crucible some six thousand 
guldens worth of small diamonds and rubies, and heated them 
strongly in a fire for a day and a night, hoping by this means 
to melt together the stones and obtain from them a large dia- 
mond of great value. It was a lucky thing for the alchemist 
that he had concealed his identity, for next day when the king 
ordered the crucible to be removed from the fire and opened, 
he found that the diamonds had all disappeared while the 
rubies were left unaltered ! They had simply burnt away 
like bits of coal. 

In the year 1771 a magnificent diamond was burnt in the 
laboratory of the chemist Macquer at Paris, and it was this 
experiment which ultimately led to the discovery of the true 
nature of the diamond. Streeter thus relates the story : 

" The fact was undoubted ; the diamond had disappeared ; 
but whither ? Had it volatilised ? Had it burnt ? Had it ex- 
ploded ? No one could say. Upon this there stepped forward a 
celebrated jeweller of Paris, by name Le Blanc, who asserted the 
indestructibility of the diamond in the furnace, stating that he had 
often placed diamonds in an intense fire to purify them from certain 
blemishes, and that they had never suffered the smallest injury. 
The chemists, D'Arcet and Rouelle, then demanded of him that 
he should make the experiment on the spot in their presence. He 
took some diamonds, enclosed them in a mass of coal and lime in a 
crucible, and submitted them to the action of the fire. He had no 
doubt that he should find them safe. But, alas ! he had sacrificed 
his diamonds ; for at the end of three hours, on looking into the 
crucible, they had utterly disappeared. The scientific men, however, 
did not long enjoy their triumph. Another jeweller, Maillard, in 
the presence of the celebrated Lavoisier, took three diamonds and 
closely packed them in powdered charcoal in an earthen pipe-bowl, 
in a strong fire ; and when the pot was taken out there lay the dia- 
monds in the powdered charcoal untouched. It was, however, 
gradually discovered that it was only by entirely shutting off the 



THE ELEMENT CARBON 219 

air and therefore the oxygen, with which carbon combines, that the 
diamonds were preserved from burning ; whereas, by the simple 
admission of air of which oxygen is a constituent part, diamonds 
burn just the same as common coal. This fact Lavoisier proved in 
1776 ; and Davy subsequently proved that the diamond contains 
no hydrogen."* 

A diamond if heated to a white heat in the electric arc 
swells up, turns black, and is converted into a valueless mass 
of graphite. 

The diamond is one of the most valuable gems (rubies, 
however, are worth weight for weight far more), those which 
are colourless being especially prized. One of the most 
beautiful of this kind is the Pitt or Regent Diamond. It 
originally weighed 410 carats (1 carat =3.17 grains or 0.2504 
grams), but after being cut it only weighed 136.25 carats. 
This gem was found by a poor slave in India at Purteal, 
who concealed it in a gash made for its reception in the calf 
of his leg. One dark night he fled away, and wandered 
through the land until he came to Madras. There, walking 
among the shipping, he saw an English skipper, and confided 
to him his secret. This scoundrel said that he knew of 
a purchaser, and lured the slave on board his ship. Here he 
treacherously murdered him, taking the diamond and flinging 
his body overboard. Some days afterwards he offered it 
to a dealer named Jamchand, and obtained £1,000 for it. 
This he ran through by all manner of excesses, and then, 
being haunted by his crime, he hanged himself. Jamchand 
sold it in 1710 to Thomas Pitt (grandfather of the great Earl 
of Chatham), at that time Governor of Madras, for £10,000 ; 
but the risk of keeping such a valuable gem was too much 
for his nerves ; he was unable to sleep at night for fear of 
thieves ; and so it came about that in 1717 he sold it to the 
Duke of Orleans, Regent of France, for £130,000. When 
that mighty catastrophe, the French Revolution, plunged 
all France into bloodshed and disorder, some robbers during 
the night got into the vast chambers of the Treasury by 
climbing in through a window and stole it. Some days 

* Streeter's " Precious Stones," quoted by kind permission of 
the author. 



220 MODERN CHEMISTRY 

afterwards it was discovered in a ditch, and thus recovered. 
Among other great diamonds, many of which have had an 
even more romantic history than the Regent, may be men- 
tioned the Koh-i-noor, now a British Crown Diamond. 
This stone is of Indian origin, and is stated to be 4,000 years 
old. Its authentic history begins about 56 B.C. One stands 
amazed to think of the long line, fading away into antiquity, 
of kings, princes, and queens, who have seen and handled 
this stone. The numerous tragedies which have been asso- 
ciated with it, and its strange wanderings, make up a romance 
as strange as any story in fiction. Its history, however, is 
too long to be related here. Among other famous diamonds 
may be mentioned the Orloff, The Star of the South, The 
Mattan, and the Hope. 

The Hope diamond is of a magnificent blue colour, and it 
has a superstition attached to it that it brings misfortune 
and disaster to all who possess it. Within the last few 
years it has been in Constantinople, and if it be true that it 
was in the possession of Abdul Hamid, that his favourite 
was wearing it when she was shot, and that nearly every 
one concerned with it met speedy death or disaster, it would 
only be in accordance with the gloomy history of the gem. 
For this is a list of the authenticated tragedies : 

Andreas Tavornia, the dia- Ruined in old age, and died 

mond merchant who sold it to of fever on a journey to the East 

Louis XIV, after bringing it home to recoup his fortunes, 
from the East. 

Madame de Montespan, who Supplanted by Madame de 

wore it. Main tenon. 

Nicolas Fouquet, who bor- Disgraced and imprisoned, 
rowed it. 

Marie Antoinette, who wore it. Beheaded. 

Princesse de Lamballe, who Torn to pieces by Paris mob. 
wore it. 

Louis XVI, who owned it. Beheaded. 

In the troubles of the French Revolution the stone was 
stolen, but mysteriously came to light again some years later, 
and in 1830 passed into the hands of Mr. Hope. Quite 
recently it has been sold. " It looks as if people were really 



THE ELEMENT CARBON 221 

getting afraid of the Hope Diamond," says The Sunday 
Observer, in June, 1909, " on Thursday it fetched only £16,000, 
though it changed hands a few years ago for £28,000. So 
long ago as 1830 Mr. Hope gave £18,000 for it, and the recent 
increase of millionaires should have sent up the price enor- 
mously. Most significant of all is the fact that even in 




Fig. 44. — Some Historic Diamonds, a, Great Mogul ; b, Star of the 
South ; c, Koh-i-noor ; d, Regent ; e, Orloff — all actual size. 

[Illustration from " Chambers's Encyclopaedia," article " Diamonds," 
reproduced with permission of the publishers.] 

America, whither it went in 1901 after Lord Francis Hope 
was permitted to dispose of it, no purchaser could be found." 
The largest diamond ever discovered either in ancient or 
modern times is the Cullinan Diamond, of 3,025 carats, 
found at Pretoria in 1905. Mr. F. Wells, the manager of 
the Premier Diamond Mine, was making a tour of inspection 
between four and five o'clock in the afternoon. Suddenly 
he saw the rays of the setting sun reflected from a bright 
object high up in the mine face. He climbed the sloping 



222 MODERN CHEMISTRY 

bank and saw the projecting edge of an enormous diamond. 
With his pocket knife, which he broke in his feverish efforts 
to dislodge the gem, he succeeded in digging it out. The 
diamond, when being shipped to England, was insured for 
£500,000, and has since then been cut into a number of smaller 
stones, and now forms part of the Crown Jewels of the British 
Throne. 

We now come to the second modification of carbon. This 
is graphite. We are all more or less familiar with it. It is 
the shiny, soft substance used for black lead pencils, for 
polishing boots and fire-grates, for lubricating revolving 
machinery, and for many other purposes. 

Graphite has a metallic lustre, and so well does it conduct 
electricity that it is actually used for making moulds on 
which it is desired to deposit metals in electro typing. Metals 
are deposited on it as on another metal. 

The substance has been called "blacklead " for centuries, 
because it looks exactly like a dull sort of lead, and like it 
marks paper. Blacklead pencils, however, are no modern 
invention. For in the year 1565 appeared a book by Conrad 
Gessner, entitled " De Rerum Fossilium Figures," in which 
is a picture and description of one of these pencils. It is 
not known how long these articles have been used, but 
certainly they are centuries old. 

Graphite is one of the most infusible and involatile sub- 
stances that we possess, and consequently is used for making 
crucibles and vessels capable of withstanding the terrific 
temperatures of the electric furnace, temperatures at which 
all other substances melt like wax and even boil. Such 
vessels have recently become very important on this account. 

We have seen when discussing diamonds that molten iron 
(and other metals as well) dissolves carbon, which crystallises 
out on cooling as graphite ; but this is not how it is formed 
in Nature. It occurs in mines in different parts of the world 
(Germany, Bohemia, United States, Siberia, Ceylon), and 
has undoubtedly been produced from coal. We may picture 
the process as follows : The earth's surface is in eternal 
motion. Hills rise out of the sea in the course of ages, while 
continents sink slowly below it. We know, for example, 






THE ELEMENT CARBON 223 

that the whole of central Europe was once a huge inland 
sea. England has been under water two or three times during 
past ages. Now, in consequence of these great earth move- 
ments, it sometimes happens that beds of coal sink to such 
great depths as to become highly heated by the intense 
internal heat of the earth. This heat, combined with the 
enormous pressure exerted by miles upon miles of rocks above, 
causes the coal to become graphite. In subsequent ages the 
crust may be uplifted again and the graphite brought to 
within mining distances of the surface. Mendeleef has 
observed this gradual transformation of coal into graphite 
as the strata sinks in the valley of Aosta near Mount Blanc* 

Graphite is now manufactured in large quantities by elec- 
trical processes. Girard's and Street's method is to send a 
powerful electric current through compressed charcoal or 
coal dust. An immensely high temperature is thus produced, 
and the carbon passes into graphite. 

In Acheson's process, which is worked in his great manu- 
factory at the Niagara Falls, a mixture of sand and coal is 
heated in a special form of electric furnace. Carbon silicide 
or carborundum is formed at first, but under the vast heat 
the silicon volatilises away and leaves behind pure graphite, 
which is much better than that which comes from the mines, f 

Graphite is produced also as a by-product when high-boiling 
hydrocarbons are distilled out of iron retorts, or when 
acetylene gas is sent through red hot tubes. 

Amorphous carbon or charcoal is the third modification 
of carbon, a variety which differs from diamond and graphite, 
in possessing no distinct crystalline structure. Many varie- 
ties exist, such as lampblack, gas carbon, and charcoal. 
Lampblack or soot is manufactured by suspending metallic 
cylinders over oil lamps, the soot then condenses on them, 
and can be purified by heating in a stream of chlorine gas, 
which removes every trace of hydrogen. 

Compressed acetylene gas slowly decomposes, giving an 
extraordinary fine form of soot. The substance is used for 

* Mendeleef : " Principles of Chemistry," Vol. 1, p. 340 (1891 Ed.). 
f A full description is given in Cassier's Magazine, Vol. 26 (1904), 
p. 24. " Some Electric Furnace Processes," by J. Wright, 



224 MODERN CHEMISTRY 

making "Chinese ink," "printers' ink," and certain black 
lacquers and varnishes. 

Gas carbon, obtained by distilling coal in making coal gas, 
is much used in electric lighting. 

Charcoal is obtained by heating sugar, wood, or bones in 
closed vessels. It has many valuable properties, being 
among other things an excellent fuel, burning without smoke 
or flame. Charcoal powder, especially that prepared by 
heating bones or blood (animal charcoal), has great disin- 
fecting and decolourising properties. The reason of this is 
that it possesses the power of absorbing various putrefactive 
gases, thus bringing them into contact with oxygen gas, 
which is also absorbed within its pores. Oxidation proceeds, 
and the gases are converted into harmless compounds. This 
is one of the reasons why the interiors of watercasks on ships 
are often charred and blackened, the layer of charcoal 
keeping the water pure during the long sea voyage. 

A piece of formless black charcoal may at first sight 
appear to have nothing particularly interesting about it. 
Yet how deceptive are first appearances ! for this, if magni- 
fied a few hundred thousand times, would be seen to have a 
structure so complex as to be beyond all power of description. 
The substance possesses a froth-like structure, and is filled 
with numberless caverns, tunnels, rooms, and galleries, 
lying thick one over the other in endless confusion. Within 
them prevails a very great attractive force, and in consequence 
of this they are rilled with closely packed molecules of gases 
which have been sucked into the dark pores and passages and 
there stored up. Thus a piece of freshly made charcoal will 
absorb no less than 170 times its volume of ammonia gas 
at ordinary temperatures and pressures. A similar process 
of absorption takes place with other gases as well. The gases 
thus stored up in these chambers are so strongly compressed 
as to be almost liquid ! At low temperatures this power 
charcoal has of taking up gases is enormously increased. An 
almost perfect vacuum may be made by absorbing the gas 
in a closed vessel by means of charcoal cooled to the 
temperature of liquid air. For the same reason charcoal will 
precipitate a great many substances from solution and 






THE ELEMENT CARBON 225 

absorb them into its pores. Thus, if a quantity of red wine- 
say claret or port — be shaken and gently warmed with a 
quantity of freshly made bone charcoal, then, on filtering, 
the liquid which comes through is found to be quite colourless. 
This property of charcoal is made use of on the large scale 
in many industries for removing objectionable colouring 
matter from syrups, sugars, and other preparations. 

Coal is simply fossilised carbon, the charred remains of 
a bygone vegetation. It is found in the older geological 
formations, reaching right up to the Tertiary Period. Coal 
occurs in every part of the world, even in regions now buried 
perpetually under thousands of feet of ice and snow — a fact 
which shows that the desolate polar regions once possessed 
a tropical climate. Vast masses of it occur buried in China, 
North America, England, and Germany. The total amount 
has been estimated as over 500 billion tons. 

Coal is largely composed of the giant club-mosses of the 
past — mosses so huge that their stems were three or more feet 
in diameter and fifty feet in length ! Most of the present 
club-mosses are only a few inches long. We also find in 
coal remains of immense ferns, with stems sometimes six 
feet in diameter and seventy feet in length. Here in vast 
swamps, crowded together in a way scarce known upon the 
earth at the present day, grew and flourished these giant 
masses of vegetation. The seas in those old days were fuller 
than at present, for their waters had not sunk into the earth 
to the same extent that they now have. They flooded the 
low-lying land and formed shallow swamps, extending over 
hundreds of thousands of square miles. Moreover, their waters 
were, perhaps, still warmed by the internal heat of the earth. 
The steaming seas warmed the air, filling it with mists and 
vapours, and making it tropical over every clime Moreover, 
the atmosphere was still far richer in carbon dioxide than at 
present, and this alone raised the general atmospheric 
temperature some degrees, and provided the vege ation with 
abundant nourishment. 

All these circumstances made vegetation grow in a way 
that is beyond our conception. In the swamps tree after 
tree arose, springing up rapidly, then decaying and dying, 



226 MODERN CHEMISTRY 

and choking up the ground with their seeds and fallen stems. 
As they decayed they fell one over the other and thus built 
up a vast undergrowth of decaying wood and vegetables. 
On this in turn grew fresh plants, only to decay and fall, 
until masses of evil-smelling, decaying vegetation, hundreds, 
perhaps thousands of feet thick were built up. These 
masses, sinking in time below the sea, became covered over 
with sediment and sand thousands of feet thick, and after 
countless ages of slow change became converted into the 
coal of to-day. To explain this we may say that when we 
heat wood or vegetable matter strongly in the absence of 
air at ordinary temperatures it blackens, turning into car- 
bon, eliminating its hydrogen and oxygen. The same change 
will take place at ordinary temperatures, heat merely acceler- 
ating a process that will complete itself entirely at ordinary 
temperatures in the course of many thousands of years. A 
chemical action which requires hundreds of years at o° C. 
to complete itself will often require only days at ioo° C. 
and seconds at a red heat. Heat is a great accelerator of 
all chemical change ; the gases which escape into coal mines 
are set free owing to these slow changes progressing within 
the coal itself. 

The coal, therefore, which we now burn in our grates is 
merely the fossilised carbon from these ancient gloomy 
forests which flourished and vanished ages before man 
trod the earth. Strange indeed they must have looked, full 
of huge ferns and mosses and hanging creepers clustering 
together in a tangled mass, with the sun's rays streaming in 
from above, vainly endeavouring to light up the darkness of 
the moist, decaying, evil-smelling ground below. 

Such forests, where coal is even now forming, may be seen 
in some parts of the world. In the valley of the Mississippi 
may be seen vast masses of vegetation, forests standing in 
swamps, above a mass of rotting timber, extending to the 
depth of several hundred feet, just such a mass as once 
existed in our coal fields when they were being formed. 

" If the reader wishes to picture to himself the scenery of what is 
now central England, during the period when our coal was being laid 
down, he has only, I believe, to transport himself in fancy to any 






THE ELEMENT CARBON 227 

great alluvial delta, in a moist and warm climate, favourable to the 
growth of vegetation. He has only to conceive wooded marshes, 
at the mouth of great rivers, slowly sinking below the sea ; the forests 
in them killed by the water, and then covered up by layers of sand, 
brought down from inland, till that new layer became dry land, to 
carry a fresh crop of vegetation. He has thus all that he needs to 
explain how coal measures are formed. I myself saw once a scene 
of that kind, which I should be sorry to forget ; for there was, as I 
conceived, coal, making or getting ready to be made before my eyes : 
a sheet of swamp sinking slowly into the sea ; for there stood trees, 
still rooted below high-water mark, and killed by the waves ; while 
inland huge trees stood dying, or dead, from the water at their roots. 
But what a scene — a labyrinth of narrow creeks, so narrow that a 
canoe could not pass up, haunted with alligators and boa-constrictors, 
parrots and white herons, amid an inextricable confusion of vegetable 
mud, roots of the alder-like mangroves, and tangled creepers hanging 
from tree to tree ; and over-head huge fan-palms, delighting in the 
moisture, mingled with still huger broad-leaved trees in every stage 
of decay. The drowned vegetable soil of ages beneath me ; above 
my head, for a hundred feet, a mass of stems and boughs, and leaves 
and flowers, compared to which the richest hothouse in England was 
poor and small. But if the sinking process which was going on 
continued a few hundred years, all that huge mass of wood and leaf 
would be sunk beneath the swamp, and covered up in mud washed 
from the mountains, and sand driven in from the seas ; to form a 
bed many feet thick, of what would be first peat, then lignite, and 
last, it may be, coal, with the stems of killed trees standing up out 
of it into the new mud and sand-beds above it, just as the Sigillariae 
and other stems stand up in the coal beds both of Great Britain and of 
Nova Scotia ; while over it a fresh forest would grow up to suffer the 
same fate — if the sinking process went on — as that which had pre- 
ceded it."* 

Now let us relate a wonderful thing. This carbon in 
the plants was obtained by them from the carbon dioxide 
(C0 2 ) in the air by the agency of sunlight. The plants 
absorbed the gas, the light decomposed it to carbon and oxy- 
gen, the oxygen was given up to the air while the carbon 
remained stored up in the tissues of the plant, to be finally 
turned into coal, dug out of the earth by man after long 
ages, and burnt again in his fires to carbon dioxide — its 
original form of combination. Thus the sunlight which lit 
up this ancient Palaeozoic world separated out the carbon ; 

* " Kingsley's Essays," Vol. 19, p. 105 (Macmillan, 1880, quoted 
by kind permission of the publishers). 



228 MODERN CHEMISTRY 

and the energy which the sun once thus expended is now 
given back to us again as heat and light in our coal fires. 
So that we may in a sense regard the heat from the burning 
coal as part of the heat and light radiated from the sun 
millions and millions of years ago ! Moreover, the oxygen 
in the air, which is roughly chemically equivalent in quantity 
to the amount of carbon found as coal, has probably all 
been for the most part derived from carbon dioxide in this 
way. It was once combined in the air with the coal we burn. 

My reader will now, I am sure, look upon a piece of ordin- 
ary coal with increased interest. For it is a very wonderful 
thing, with a very wonderful history behind it, a history 
fraught with the mightiest cosmical effects, and most inti- 
mately bound up with the life of man and beast. Each piece 
of coal is old, far older than any of the hills around us. It 
has endured while untold races of men and animals have gone 
by and faded ; it was there when vast reptiles roamed in 
gloomy swamps and man was not as yet ; in comparison to 
it man is a thing of yesterday. 

Most elements have strong chemical attractions for some 
elements and very weak attractions for others. Thus, 
oxygen has a very strong attraction for hydrogen but hardly 
any at all for gold. Carbon, too, conforms to this rule, but 
with this difference : while other elements exert their 
strongest attractions on elements different from themselves, 
carbon has the remarkable peculiarity of exerting its greatest 
attraction on its own atoms.* They combine together with 
extraordinary power. 

This fact explains almost all the remarkable peculiarities of 
carbon. It explains, for example, its extraordinary invola- 
tility. The highest temperature yet produced upon the earth 
barely suffices to volatilise it ; but on the sun, that stupen- 
dous mass of white-hot rushing gas, the heat is so incredibly 
great that even carbon boils and forms vast whirling masses 
of vapour surmounted by dazzling white-hot clouds of con- 
densed soot — clouds which give the sun much of its 
brilliance. 

* Full evidence in support of this view is given in the author's 
work, " Researches on the Affinities of the Elements," 






THE ELEMENT CARBON 229 

It explains, too, the wonderful chemical inertness of carbon 
at ordinary temperatures. For before a substance can take 
part in a chemical change its molecules must, partially at 
any rate, split up into their component atoms. But obviously 
molecules whose atoms are very strongly attracted together 
will not split up so, and consequently are indifferent towards 
other atoms. This is the reason why carbon is at ordinary 
temperatures one of the most chemically inactive substances 
known. It will not combine with any other element, nor will 
it dissolve even in the strongest acids.* 

The unalterability of charcoal under the action of atmo- 
spheric influences which produce changes in the majority of 
stony and metallic substances is often made use of in practice. 
For example, charcoal is frequently strewn in boundary 
ditches. The surface of wood is often charred to render it 
durable in marshy soil where the wood itself would soon rot. 
In chemical works the chambers through which acid vapours 
pass are filled with coke, because at ordinary temperatures 
it resists the action of the most energetic acids. Indian ink 
and printers' ink will last for centuries without fading. They 
owe their stability to the unalterability of carbon under 
atmospheric influences, being composed of fine carbon par- 
ticles. The manuscripts of Herculaneum were written with 
carbonaceous ink, yet after 1800 years they are unchanged ! 
But this is only at ordinary temperatures. At a red or 
white heat carbon awakes from its deathlike sleep and be- 
comes one of the most chemically active elements known, 
burning in oxygen, reducing metals from their ores, and at 
the still higher temperatures of the electric furnace com- 
bining with almost all the metals to form carbides. 

This intense self-attraction of carbon explains, too, the 
astonishing complexity of its compounds. For the carbon 
atoms combine together to form frameworks of vast com- 
plexity. By the attachment of atoms of hydrogen, oxygen, 

* Certain bacteria are stated to have the power of oxidising carbon 
at ordinary temperatures. If this is really so it furnishes us with 
another example of how enormously the power of living matter to 
carry out chemical actions transcends that of the chemist working in 
his laboratory. 



230 



MODERN CHEMISTRY 



sulphur, nitrogen, and phosphorus to these frameworks we 
get that tremendous array of complex organic substances 
found in animal and in vegetable matter, as well as in the 
numberless artificial dyes and drugs now manufactured. 
What a wonderful glimpse we obtain into the mystery of 
living matter when we study the complex bodies produced 
as the product of its incessant change ! a single molecule 
of starch — the constituent 
of many plant cells — has 
according to Brown and 
Morris the formula C 1200 
H 2 o o o O 1000 , being com- 
posed of 4,200 atoms all 
linked together ! Cellulose 
— the hard skeleton of 
wood, cotton, and plants 
generally — has an even 
more complex molecule. 
Its empirical formula may 
be represented by the little 
expression C 6 H 10 5 , 
but its actual molecule 
may be fully a thousand 
times greater, viz. : C 6 
-^ioooo C^ooo* It seems 
hopeless to attempt to 
make such a substance. 
Every one knows the in- 
finite number of configura- 
tions in which it is possible to arrange 21,000 articles. In 
the words of a recent writer,* " Given that a certain 
unseen house consists of 6,000 pieces of wood, 10,000 
pieces of stone, and 5,000 pieces of iron, build its dupli- 
cate blindfold ; this is a problem somewhat more or less 
difficult than the synthesis of cellulose. Yet every plant 
performs this feat with unerring certainty when it builds 
up its cellulose skeleton — how no one has the remotest idea." 
Equally complex are certain sugars, albumens, and other 
* " The Chemistry of Commerce," by Prof. Duncan (1907). 




Fig. 46. — The Benzene Ring. A ring 
of Six Carbon Atoms (the tetrahe- 
drons) with other atoms attached. 
Many of the compounds contained 
in Coal Tar consist of molecules 
containing such rings. 



THE ELEMENT CARBON 



23* 



bodies existing in a state of ceaseless change in living plants 
and animals. Their molecules consist sometimes of thou- 
sands and thousands of carbon atoms linked together in long 
strings. The sugars are long chains of carbon atoms to 
which are united hydrogen and oxygen atoms. One of the 
best known sugars is cane sugar, C 12 H 2 2 O x 1 ; whose 
molecule is believed to be built up in this way : 







wt0tt — * 


0\ 


H 2 C.OH 




"Ch"" 

1 






V 


HO. C.H. 

1 
HO. CH 

^ ! 

1 




oK 


/ c< H 
c< H 

\ I OH 
^ CH 


HO. 


C.H 

| 






HO. CH 2 


HO 


CH 2 










Cane 


Sugai 







The dashes represent how the atoms are linked up in the 
molecule. Of course many of the sugars occuiring in the 
animal and vegetable body are far more complex than this, 
while at the same time still simpler sugars exist. Among 
the more simple frameworks are those occurring in camphor, 
indigo, and allied bodies : 



CH 2 CH CH, 

H 3 C. C. C H 8 



CH r C- 



-CO 



CO CO 

>C 6 H 4 



in 





NH NH 

Indigo. 



Camphor. 

Similar frameworks occur in a large number of dyes, a 
few of which are pictured in the illustration. 



232 



MODERN CHEMISTRY 



When we reflect that in these 
innumerable numbers of vastly 
complex molecules the atoms are 
not at rest, but are in eternal 
motion like the planets round 
the sun, each performing its own. 
little evolutions in the molecule 
with enormous rapidity and great 
regularity — as the wonderful ab- 
sorption spectra of such bodies 
prove — we seem to obtain a dim fig. 47 . — Framework of 

glimpse Of the Wonders that we Carbon Atoms occurring 

would see in organic nature if m amp or ' 

we only possessed the means to render visible the molecules. 

In this case no doubt a new and undreamt of universe 







Fig, 48. — Framework oi Carbon Atoms occurring in Indigo, 




49. — Framework of Carbon Atoms occurring in a 
Complex Organic Dye, 

would burst upon our view, a universe rivalling in complexity 
the stellar universe above. 1 Think of it — each carbon 



THE ELEMENT CARBON 233 

atom consists of 20,000 smaller particles, each oxygen 
atom of 30,000, while a single complex molecule like that 
of cellulose may well contain over 300 million electrons 
— as^many particles as there exist visible stars in the universe 
around us ! Such a molecule is in itself a universe, and yet 
each stick and each leaf contain countless billions of them. 
The mind reels, the imagination fails before such infinite 
numbers, such infinite complexity. Think of the countless 
leaves of a forest, think of the numberless plants that have 
lived and died in the innumerable ages of the past, and then 
realise that each one of these leaves, each one of these 
plants, was a collection of untold myriads of atomic uni- 
verses ! We thus obtain a vision of Nature beside which 
the grandest epic ever penned by human hand seems empty 
and colourless. 



i 



CHAPTER XI 

CARBON DIOXIDE 

A coal fire gleams and burns away. It dies down into 
glowing embers, and then into a handful of ash. The coal 
has vanished apparently into thin air. In seaports you may 
see men heaping thousands of tons of coal into the bodies of 
immense liners. Later, descending beneath the decks to 
where mighty engines whirl and vibrate, driving the huge 
vessel through the sea, you will see stokers, hot and per- 
spiring, naked to the waist, hurling this coal into the huge 
furnaces which drive the boilers. The vessel starts on her 
voyage with thousands of tons of coal in her bunkers. 
She arrives at the end of her journey with this almost all 
gone, vanished down the throats of her furnaces, leaving 
only a trace of ash behind. In 1907 over a thousand million 
tons of coal disappeared in the same way in the fires of the 
civilised world. Whither has this vast quantity of coal 
gone ? Has it been destroyed, annihilated by the very act 
of burning ? No ! Science tells us that matter cannot be 
destroyed in this way. These millions of tons of burnt coal 
still exist, they exist in the air in the form of an invisible 
gas. Yes, strange as it may seem, the coal in burning has 
turned into an invisible gas containing carbon and oxygen. 
Indeed, all the coal now stored in the earth was once, ages 
ago, united to the oxygen of the air and floated free, in the 
form of this gas, in the winds of the primeval world. How 
then did this gaseous carbon turn to solid coal ? In this 
way : The gas was laid hold of by some living plant, which 
sucked it in through its leaf pores, drank it in through its 
rootlets, and turned it into wood. The tree died, decayed 
to vegetable fibre, was buried, lost its oxygen, and the carbon 
in it turned to coal. A man digs this coal. He throws it on 

234 



CARBON DIOXIDE 235 

the fire— seemingly a black dead lump, but really a universe 
of whirling vibrating atoms. A corner, an atom of it warms 
until it reaches its ignition point. Then it awakens after its 
long sleep of ages ; each atom is seized by a hunger for that 
very oxygen that it lost millions of years ago, combines with it, 
and flies away in the form of this invisible gas. The gas thus 
produced is known to us all. Every time we breathe, it 
rushes from our lungs, produced by a process of slow combus- 
tion ; for we, too, are burning away, just like the coal, into 
the same gas. It is stored up in countless millions of tons 
in limestone and chalk, and issues from them when they are 
burnt to quicklime. Many and many a poor tramp, lying 
down by the side of a burning lime kiln to keep himself 
warm, has been overcome by the deadly gas pouring from it 
and has passed away in sleep into that land whence none 
return. 

Every time we open a soda-water or lemonade bottle, 
every time champagne or beer leaps foaming forth from its 
glass prison into a tumbler, we see this gas rushing out in the 
form of millions of bubbles in the sparkling liquid, churning 
it into froth. In brewers' vats it is present to the extent 
of thousands of cubic feet, and is produ ed by the process of 
fermentation. Lastly this gas is about us, present in the 
very air we breathe, feeding and sustaining the great timber 
trees and the beautiful green vegetation which clothes the 
world about us. 

What is this gas ? Chemists call it carbon dioxide. Its 
older name is carbonic acid gas. It consists of the accumula- 
tion of millions of tiny molecules speeding through space at 
the rate of a quarter of a mile a second, each molecule con- 
sisting of a carbon atom united to two oxygen atoms. 
Picture each molecule as a tiny planetary system with the 
central carbon atom as sun and the two oxygen atoms 
revolving about it as planets, and you will have a realistic 
interpretation of the formula CO a which chemists attribute 
to it. 

The reader, too, may prepare it, and that with ease. All 
that he has to do is to place some lumps of marble in a 
bottle or flask, pour on it some acid (even a weak one like 



236 MODERN CHEMISTRY 

that contained in vinegar will do ; usually, however, hydro- 
chloric acid is used), and at once, amidst a strong efferves- 
cence, he will see the gas being liberated in the form of 
thousands of little bubbles. The reaction has taken place 
tccording to the following equation : 



CaC0 3 + 


2HC1 = 


CaCl 2 + H 2 + C0 2 


Calcium Carbanate 


Hydrochloric 


Calcium Water Carbon 


(Chalk) 


Acid 


Chloride Dioxide. 






Now let us describe its properties. It is colourless. It is 
invisible. It suffocates. A light plunged into it is extin- 
guished as if plunged under water. The fiercest fires may 
be quelled by pouring it upon them. But it extinguishes 
animal life in the same way that it extinguishes fire, — for are 
not the two allied ? Men have unwittingly entered chambers 
and underground cellars filled with this gas, and have died. 
Indeed, its presence in these is a real danger, because of its 
great heaviness ; for the gas can be poured like water from 
one vessel into another, so heavy is it. Soap bubbles may 
be made to float upon its invisible surface much as wood 
floats on water. Consequently it runs like water into hollows 
and there collects. In some parts of the world are found 
real death valleys, hollows shunned by man and beast, 
because to enter them is fatal. The reason is that carbon 
dioxide gas issues out of the earth from fissures in the floors of 
these valleys, and then fills them as water fills a lake. The 
most famous of these deadly depressions is the " Valley 
of Death " in Java. It is a deep, dark, wooded valley, the 
crater of an extinct old-world volcano. Tigers, wild-boars, 
and even men, attracted by the quiet and shelter of the spot, 
have been known to descend and perish miserably by 
suffocation. Yet the flow of gas is intermittent. Some- 
times it is quite safe to enter, scarce a trace of gas being found, 
while at other times it wells out in large volumes and fills 
the valley. Its bottom is said to be strewn with skeletons of 
animals which have perished in its depths. Indeed, some say 
that human skeletons have been observed lying in the under- 
growth, the remains of poor wretches who have wandered 
unknowingly into this death-trap. The " Death Gulch " 



CARBON DIOXIDE 237 

of Western America is another such valley. In it dead 
bears and animals are often found. All these localities are 
in volcanic regions, for in all such regions vast amounts of 
this deadly gas pour out into the air, not only through the 
throats of volcanoes, but also through the ground surround- 
ing them, and, long after the volcanoes are extinct, the effect 
often continues. * Thus in the woods surrounding the Laacher 
See, itself the water-filled crater of a prehistoric volcano, 
there is a depression constantly filled with this gas. Insects 
and birds flying to this spot perish. In this whole region the 
gas streams out of the earth through hundreds of outlets, 
and tends to collect in the cellars of houses. Some tragedies, 
indeed, have been thus caused. Only a few years ago Dr. 
Creighton, the former bishop of London, was walking round 
this beautiful lake, together with his wife and daughter. 
They were overtaken by a thunderstorm, and sought shelter. 
Soon a peasant girl came running to them in great trouble, 
saying that her sweetheart had fallen down, and she was 
afraid that he was hurt as she could not make him answer. 
She led them to a deserted building, and there at the bottom 
of a flight of ruined steps they could see the dim form and 
white face of a man. The bishop rushed down the broken 
steps and cautiously put his head in. The room was full 
of carbon dioxide and he could not breathe. Filling his 
lungs with fresh air, he plunged into the cellarlike building 
and dragged the man as far as he could. After several 
vain efforts at last he got him out into the open air. It was, 
however, too late. The man was dead. 

In a cave near Naples, the Grotto del Cane, the carbon 
dioxide comes pouring out from the earth from fissures in the 
floor, and collects in the cave to the depth of two or three 
feet. Small animals, such as dogs, when respiring the impure 
air, drop senseless ; while a man breathing the pure air above 
this level is unaffected by the gas. If, however, the man 
were to sit or lie down he would be speedily overcome and 
suffocate. 

After an eruption at Vesuvius carbon dioxide gas has been 
known to come off from the ground in such quantities as to 
poison hundreds of hares, partridges, and other small animals, 



238 



MODERN CHEMISTRY 



while at the same time the cellars of the houses at Naples 
became filled with it. 

Undoubtedly the greatest masses of carbon dioxide enter 
the air from volcanoes, especially great torrents of it are 
evolved from the craters of those which exist in South 
America. 

Now a solemn thought arises. If this death-bringing gas 
is even now ejected in such volumes from the interior of the 
earth, what must have been the case in past ages when its 




Fig. 50. — Dog Grotto near Naples (Grotto del Cane). 

internal fires raged far more furiously than at present ? 
We know that in these early times the earth often cracked 
across, and from the vast fissure thus produced huge torrents 
of molten rock and gas were belched forth and inundated 
the surrounding plains. It may, indeed, have happened, 
time after time, in these terrible ages, that such vast quanti- 
ties of carbon dioxide were periodically poured forth over the 
land as to destroy all animal life over whole districts. Even 
in our own times terrible disasters have occurred owing to 
the belching forth of suffocating vapours during volcanic 
eruptions. Thus in 1783 a terrific volume of lava burst 
forth from the great volcano Skaptar Jokul, in Iceland, and 



CARBON DIOXIDE 239 

such huge volumes of poisonous gas were evolved simul- 
taneously that 9,000 men, 11,000 cattle, 28,000 horses, and 
190,000 sheep are said to have been suffocated ! The elder 
Pliny was suffocated, over 2,000 years ago, by heavy gases 
pouring over the ground from Vesuvius when she burst into 
that eruption which overwhelmed Pompeii and Hercula- 
neum. Apart from the enormous quantities of gas pouring 
out from subterranean depths in volcanic regions, it is well 
known that the ground itself evolves it. One acre of good 
garden land in summer evolves more than six tons of carbon 
dioxide. It is produced by the oxidation of organic matter 
in the soil. Hear what Dr. Leonard Hill says about this 
matter : 

" Processes of oxidation are constantly going on in the soil which 
result in the impoverishment of the air in wells and mines, and the 
formation of carbonic acid. Iron pyrites (FeS 2 ) is decomposed by 
moist air, FeS0 4 is formed, and sulphur is oxidised to SO a . The 
SO 2 combines with water to form H 2 S0 3 ; and this, in its turn, 
oxidises to H 2 S0 4 . The sulphuric acid thus formed, coming into 
contact with the carbonate of lime (chalk or limestone) in the soil, 
evolves carbonic acid. Air impoverished by such oxidative pro- 
cesses becomes insufficient to support combustion, when the oxygen 
tension falls from the normal 21 to 17.3 per cent, of an atmosphere. 
The presence of such impoverished air is shown by the extinction of 
a candle or lamp. Pure choke, or " black-damp," as such deoxygen- 
ated air is called, contains 85 to 95 per cent, nitrogen, and 15 to 5 
per cent, carbonic acid. The amount of black-damp formed in mines 
is enormous, 2,000 to 5,000 cubic feet per minute is a common quantity, 
and the oxidative processes which produce it are the chief source of 
heat in mines (Haldane). Choke-damp comes out from the soil into 
the mine or well, especially when the barometer is falling."* 

It is no wonder, therefore, that old wells, and shut-in 
subterranean passages, such as occur under old castles and 
ruins, and in disused mines, often get filled with the gas. 
Any one walking incautiously into one of these places may 
easily be suffocated, and all the more easily because the dis- 
comfort felt by the person gradually advancing into increas- 
ingly bad air is often very slight, and gives little or no 
warning of danger. Consciousness is suddenly lost, and 

* Lecture delivered at the North Staffordshire Institute of 
Mining and Mechanical Engineers, January 13, 1908. 



240 MODERN CHEMISTRY 

unless the victim can be instantly removed to good air, 
his life is in great danger. Hence before entering into such 
a cellar the air must be always tested to see whether a candle 
will burn in it. 

Although pure air contains only 0.03 per cent, of carbonic 
acid, the air of crowded halls may increase to 0.5 per cent. 
No noticeable effects, however, are produced until the per- 
centage of gas increases beyond 3 per cent., when a painful 
headache is often caused to those breathing such air. An 
increase beyond this brings about panting, and greatly 
diminishes the capacity for work, death ensuing rapidly when 
the percentage reaches 25 per cent, and over. On holding 
the breath as long as possible, as when diving under water, 
the air of the lungs is found to contain about 10 to 12 per 
cent, of carbon dioxide. Normally there is about 5 per 
cent, of carbon dioxide in human breath. Carbonic acid 
is used by hygienists as an indicator of efficient ventilation, 
not because it is poisonous, but because it serves as an index 
of the contamination of the air by bacteria and the effluvia 
which arises from the bodies of men. It is these effluvia, 
and not the carbonic acid, which have such a bad effect on 
health. 

Men and animals are continually breathing out carbon 
dioxide into the air in very considerable quantities. All 
animals, in fact, are slowly burning away in the oxygen of 
the air, and it is the heat produced by this means which keeps 
our bodies warm and sustains life. Men, bulls, sheep, 
horses, and other animals have been placed in enormous 
hermetically-closed jars, and by carefully analysing the gases 
evolved during respiration, it has been found that a man 
breathes out 900 grams (nearly two pounds) of carbon dioxide 
per day, or about twenty-two tons in a lifetime of seventy 
years ! The whole human race throws daily into the air over 
1,000,000 tons of this gas ! When we consider the countless 
millions of men and animals who have lived and died during 
the innumerable ages of the past, we can gather some dim 
idea of the enormous quantities of carbon dioxide which have 
been poured into the air from this source. Yet this is not 
the only, nor even the chief source of the gas. In 1907 there 



CARBON DIOXIDE 241 

were burnt no less than 1,080 million tons of coal, which must 
have produced well over 3,400 million tons of the gas, or 
nearly ten times as much as was evolved in the breath of the 
whole human race during the same period of time ! By far 
the greatest quantities of carbon dioxide are poured into the 
air from the earth's interior through the mouths of volcanoes, 
being thrown out from the cooling silicates in the upper 
layers of the earth's body. 

Now this volcanic action has been going on for ages, which 
stretch back in a dim illimitable vista as far as the geological 
history of our planet takes us. For many hundreds of 
millions of years, both animals and volcanoes have been 
continually belching forth this gas ; and yet we find that 
there is only three volumes of the gas in ten thousand of air 
— a quite minute percentage. So small is this quantity 
that at the present rate at which the carbon dioxide is being 
poured into the air a few hundred years, certainly far less 
than 350 years, would double the proportion in which it is 
contained in air. It is obvious, then, that there must be 
agents which remove the carbon dioxide from the air 
almost as swiftly as it is thrown into it. One such agent, 
and perhaps the chief one, is the process of weathering. 
The carbon dioxide is absorbed by rocks. The earliest and 
most primeval rocks, those which are cast forth by volcanoes, 
and which formed the molten glowing surface of the early 
world, consist of compounds of silicic acid with alumina, 
lime, magnesia, iron, and sodium. These stones are gradu- 
ally attacked by the carbon dioxide of the air in such a man- 
ner that the lime, magnesia, and the sodium form soluble 
carbonates, which are washed away by the streams and 
rivers into the sea. Here the millions of sea animals and 
plants assimilate the magnesium and calcium carbonates 
and deposit it as shell or coral around them. Vast rocks 
are thus built up of these precipitated carbonates ; sometimes 
they occur in beds thousands of feet thick, and covering 
hundreds of thousands of square miles of the earth's 
surface. In them are stored enormous quantities of 
carbon dioxide, all of which was absorbed from the 
atmosphere by the process of weathering. Hogbom caj- 



242 MODERN CHEMISTRY 

culates that in the limestones and dolomites there exist 
at least 25,000 times as much carbon dioxide as is at 
present in the atmosphere. Chamberlin comes to about 
the same result. In other words, the amount of carbon 
dioxide withdrawn from the atmosphere in past times 
by the process of weathering and now stored up in the 
rocks in the form of carbonates exceeds the whole present 
volume of the atmosphere some 750 times ! The wonder 
grows when we learn that these estimates are probably far 
too low. The amount of carbon dioxide which must have 
existed in the early atmosphere of the earth was simply 
enormous, and baffles all attempts to realise clearly. These 
huge original amounts have all disappeared within the earth's 
interior, chemically combined with the rocks, except the minute 
fraction which now exists in the atmosphere. Even to-day 
this absorption of carbon dioxide is going on, and in conse- 
quence of it the mightiest cliffs and hardest rocks rot away 
in time, and are converted into soft soil on which vegetation 
can take root and flourish. 

There is also another process which takes from the air its 
carbon dioxide ; and that is vegetative growth. In early 
spring, no doubt you have often been struck with the beauty 
of the rich green colour of a sun-lit landscape. This green, 
so beautiful and soft, is due to the presence of a mysterious 
colouring matter called " chlorophyll," whose exact con- 
stitution has not as yet been made out. When sunlight 
gleams on this what really happens is that myriads of minute 
pulsations of the ether (we call them light) burst each second 
upon this complex chemical compound, just as waves 
break upon the sea-shore, and set its atoms swinging. When 
so agitated the chlorophyll possesses the power of sucking in 
from the air the carbon dioxide it finds in it, decomposing 
it by means of a series of very complex changes not yet 
understood, absorbing the carbon and evolving the oxygen, 
thus : 

co 2 c + 2 

Carbon Dioxide Carbon Oxygen. 

Holmes has expressed this fact in beautiful language : 



CARBON DIOXIDE 243 

" The great sun 
Girt with his mantle of tempestuous flame 
Glares in mid-heaven ; but to his noontide blaze 
The slender violet lifts its lidless eye 
And from his splendour steals its fairest hue. 
Its sweetest perfume from his scorching fire." 

Now notice a wonderful thing about this action. This 
carbon dioxide is a very stable body. A very high tempera- 
ture of 1,200-1,300° C. is required to partially decompose it. 
Yet the plant performs this difficult operation at ordinary 
temperatures, utilising the energy of the sunlight ! We see, 
therefore, how immensely more potent than ourselves to 
effect chemical change is that mysterious everchanging 
complex of atoms called living matter. Watching on a 
sunny summer day the quivering leaves in a woodland 
district or the waving blades in a wheat field, we might 
easily imagine that we are contemplating an ideal state of 
lazy enjoyment. But never were we more mistaken. All 
the time the surfaces of the leaves are in ceaseless activity, 
drinking in the carbon dioxide through every pore, decom- 
posing it by mighty forces at work within the leaves, rending 
its atoms apart, and storing them up in its body. 

This has been going on from times immemorial, ever 
since the first green plant came into existence hundreds of 
millions of years ago. The small amount of carbon dioxide 
in the air thus feeds and su] vports all the rich vegetation 
which clothes our planet with a garment of green. And 
indirectly it supports us as well, for we, like all other animals, 
depend for our nutriment upon the plant world. That Nature 
can make so much out of so little is, indeed, truly wonderful. 

The fixation of carbon dioxide by plants is part of a vast 
cosmic process going on ceaselessly, not only in our world 
but perhaps in myriads of the innumerable worlds of space. 
You must all know that the sun is a mighty white-hot globe, 
over a million times vaster than the earth. Its surface is 
in a state of terrific movement. Vast flames of gas and 
vapour rush up each second at the rate of hundreds of miles 
a second to the height of many thousands of miles. In 
consequence of this there streams from it each second 



244 MODERN CHEMISTRY 

incredible amounts of heat and light into the endless depths 
of space. Think, in a single second there rushes from the sun 
as much heat as could be produced by the combustion of 
16,400 billion tons of coal ! The earth is bathed in this 
mighty stream of heat and light, and has been for ages. 
True, it only receives the 2,128,000,000th part of it. Yet, 
excepting the tides and the energies depending upon the 
internal heat of the earth, to it is due almost every form of 
energy upon this globe. All movement of air and water, 
from the mighty devastating hurricane to the gentlest sum- 
mer breeze, from the thundering cataract to the ripple on 
the sea, all snow and rain, all thunder and lightning, are 
but the products of this solar energy. Beating upon the 
earth for untold ages it has produced — how we know not — 
a responsive action. 

" The whole earth set herself the task of storing up this light 
which streams earthwards from the sun, of converting the most 
volatile of all power into a rigid form, thus preserving it for her pur- 
pose. To this end she overspread herself with organisms which, 
living, take in the solar light, and by the consumption of its energy 
incessantly generate chemical forces. These organisms are plants ; 
the vegetable world is the reservoir in which the fugitive solar rays are 
fixed, suitably deposited, and rendered ready of useful application."* 

We have just seen how they fix these rays. It is believed 
by many chemists that all the oxygen now in the air was 
thus set free by the ancient action of sunlight and green 
vegetation on the carbon dioxide in the air. The carbon 
is at first stored up in the plant tissues ; thence it is de- 
voured by plant-eating animals (and consequently by flesh- 
eating, which prey upon the herbivorous), and in their 
bodies is oxidised or burnt again to carbon dioxide, and 
breathed out again into the air, only to be absorbed again by 
plants, split again by sunlight, and again taken into the 
animal body. Thus there occurs in Nature a ceaseless 
circulation of carbon, a circulation caused and maintained by 
the sun's rays. The carbon now in our bodies, in every piece 
of wood and grass about us, has thrilled in the living bodies 

* Mayer's words are here quoted, from Proctor's " Old and New 
Astronomy," p. 333. 



CARBON DIOXIDE 245 

of untold myriads of long-vanished races of animals and 
plants, races stretching back in almost infinite succession 
into the dim mists of past time. As the ceaseless ages roll 
onwards like an ever-flowing tide, sweeping us away and 
reducing our bodies to their component atoms, our carbon 
will continue to circulate long after our very memory has 
vanished from the world, in the bodies of animals and 
plants, living in a sun-lit world and enjoying life, millions 
of years hence ! Very strange, but still quite true. * 

Thus we realise- that all vegetation, and indirectly, all 
animal life as well, owes its existence to the sun's rays acting 
on the carbon dioxide in the atmosphere. Without this 
mighty stream of energy pouring continually upon the earth, 
no living thing could exist in the waters, in the air, or on the 
land. Man himself owes all power, his food, his coal, his 
navies, trains and great artillery, to the sun's amazingly 
profuse yet steady emission of light. Yet our tiny earth 
is but a dust speck floating in infinite space ; and the suns 
of the universe which sparkle and gleam down at us at night 
emit light quite as profusely as, and often on a far vaster 
scale than, our sun. We cannot but believe, then, that 
the dark little worlds wheeling round them are fitted with 
similar contrivances for arresting and storing the vast 
streams of energy rushing ceaselessly past them into the 
void and silence of space. 

Do those processes which remove the carbon dioxide from 
the air exactly balance those which throw it into the air ? 
The answer of science is : No ! Most careful investigations 
of American geologists, amongst whom Chamberlin may be 
especially mentioned, have shown that the carbon dioxide 
is being absorbed by rocks at such a rate that it will require 
a period of time between 5,000 and 18,000 years to use up 
that which is already in the air. The rate at which carbon 
dioxide is being actually produced by the burning of coal, 
petroleum, etc., exceeds this fourteen times over ! Then 
there still remains the absorption of the gas by plants to be 
accounted for. The famous chemist Liebig estimated 
that the amount of water-free organic matter produced by 
an acre of ploughed land, meadow, or forest, is about the 



246 MODERN CHEMISTRY 

same, namely, about one ton weight per year in Central 
Europe. Now, in many tropical countries the growth is far 
greater than this, while in other parts, in the deserts and 
arctic regions, it is much less. Arrhenius, therefore, assumes 
that Liebig's number will hold as an average number for 
the whole solid land surface of the globe, and calculates 
on this basis that plants absorb yearly no less than 13,000 
million tons of carbon from the air, or about the fiftieth part 
of the carbon dioxide in the whole atmosphere. Since this 
is twelve times greater than the amount of carbon given to 
the air by the burning of coal, it is clear that if all the plants 
were to deposit all their carbon in the form of peat or coal, in 
a very few years the air would be robbed of every bit of 
its carbon dioxide, and consequently all plant life, and with 
it all animal life, would come to a more or less abrupt end. 
Luckily for us, however, plants do not do this. Of the total 
amount of carbon taken by them yearly from the air only a 
fraction of a per cent, is deposited as peat or coal, and so is 
lost. The rest goes back, either by oxidation or decay, into 
the atmospheric carbon dioxide again. It is, indeed, believed 
that the amount of carbon dioxide in the air, far from dimin- 
ishing, is actually increasing, and that pretty rapidly. 
The enormous and increasing amount of coal burnt every 
year is probably throwing more carbon dioxide into the air 
than is removed by the agencies above discussed. Besides 
this, volcanic action, the effects of which have been especially 
disastrous of recent years, seems to be increasing, and there- 
fore the amounts of carbon dioxide yielded to the air by this 
means is also increasing. One circumstance which points 
to this conclusion has been discussed by Arrhenius.* He 
shows that the amount of carbon dioxide over the sea and 
small islands is about 10 per cent, less than that over 
continents, in other words, the sea is steadily absorbing 
carbon dioxide. Now, if the amount of this gas had remained 
unchanged in the air for vast periods of time, the amount 
of carbon dioxide dissolved in the sea would have had plenty 
of time, through absorption, to come into a state of equili- 
brium with that found in the air. If the sea is absorbing 
* Das Werden der Welten, p. $j (1908). 



CARBON DIOXIDE 247 

carbon dioxide from the air, this shows that it stands in 
equilibrium with an air containing less carbon dioxide 
than our present atmosphere contains. In other words, 
within recent years the amount of carbon dioxide in the air 
has increased. 

If this be so, we must next inquire whether this will have 
any influence upon us, and upon plant life, and upon the 
weather. Arrhenius answers : Yes, and that a favourable 
one. In the first place an increased amount of carbon 
dioxide will greatly increase the mean temperature of the 
atmosphere all over the earth's surface, thus making it 
milder. In the second place, there will be more carbon diox- 
ide in the air for plants to feed on, and thus vegetation will 
tend to become more luxuriant. It appears that this carbon 
dioxide has a wonderful power of absorbing non-luminous 
heat rays, and of letting visible light rays go through. Thus 
the rays of the sun can reach the earth, strike the soil, warm 
it, and thus be converted into invisible dark heat rays such 
as are emitted from a kettle of boiling water, or from hot 
steam pipes ; but when these invisible heat rays try to get 
away from the earth again, they cannot. The carbon 
dioxide in the surrounding air catches them and bottles 
them up, and the greater the amount of carbon dioxide in the 
air the greater is this effect, and so the higher the general 
temperature of the atmosphere. Arrhenius has calculated 
that if all the carbon dioxide in the air— it is only present 
to the extent of 0.03 per cent. — be removed the temperature 
of the earth's surface would sink nearly 21 C. As a conse- 
quence of this lowering of temperature the quantity of 
water vapour in the air would diminish, thereby causing 
an almost equally great further fall of temperature, and 
converting the whole earth into the state of the arctic 
regions. If the amount of carbon dioxide in the air were to 
sink only half its present amount, this would be sufficient 
to lower the general temperature some 4 C, and ihus give 
to England the temperature of Sweden. 

On the other hand, supposing the amount of carbon diox- 
ide were to double itself in the air, the general temperature 
would increase bv 4° C. If it were to increase fourfold, the 



248 MODERN CHEMISTRY 



rise of temperature would be actually 8° C, and restore to 
England the semi-tropical climate she is known to have 
possessed in very ancient times. 

Now notice how the sciences of chemistry and geology are 
interwoven. It is well known that in geological history 
very great temperature variations have taken place. Im- 
mediately preceding historical times was a period when the 
average temperature was 2° C. higher than at present. This 
is known because we find the fossil remains of shrubs like 
the hazel-nut flourishing in places where, on account of the 
more severe temperature conditions now prevailing, they 
cannot exist at all at the present time. Before this time 
was the terrible glacial age, which covered all Central 
Europe and Great Britain as well, with a vast ice-sheet, some- 
times thousands of feet thick, covered them up, buried 
them, and turned them into desolate arctic wastes, such as 
Greenland is now, and held them so for a hundred thousand 
years ! Before this time there went another series of long, 
long ages, when a tropical climate flourished, when tropical 
plants blocked up the Thames valley, and tropical animals 
wandered over the country, and when the temperature was 
8 or 9 C. higher than at present. These are truths proved 
beyond all doubt by science. What caused these great 
temperature changes ? Many chemists and geologists, 
among whom may be mentioned Hogbom, Stevenson, and 
Arrhenius, assert that it was the varying amount of carbon 
dioxide in the air. 

We know that the amount of carbon dioxide now in the 
air is so small that actually the burning of coal in industrial 
processes pours into it every year the six-hundredth part of 
its present amount, and therefore would double the quantity 
in the air in some six hundred years. It is true that the 
sea here acts as a mighty regulator and absorbs nearly 
five-sixths of the carbon dioxide thus produced, yet, in spite 
of this, it is certain that the minute proportion of carbon 
dioxide can be noticeably increased by industrial processes 
in the course of a few hundred years. This alone proves 
that there is no great constancy in the amount of carbon 
dioxide in the air, but that it has probably undergone great 



s 



CARBON DIOXIDE 249 

variations in past times. Indeed, in times of great volcanic 
activity such huge volumes of this gas are poured into the 
air as would certainly modify the proportions present. 
Now it has long been known that in the different phases 
of the world's geological history volcanic action has been 
very unequal. There have been periods of volcanic repose, 
which have lasted for hundreds of thousands of years, 
followed by periods of exaggerated activity, when vast 
quantities of lava were poured forth simultaneously in the 
most widely separated regions. Professor Freeh, of Breslau, 
has, indeed, recently endeavoured to prove that periods of 
violent volcanic action have always coincided with a warm 
tropical climate, while periods of volcanic rest correspond 
with ages in which a low temperature reigned. In the great 
ice-age itself volcanic action almost entirely died out, while 
both the periods at the beginning and end of the great terti- 
ary age were extremely warm, and at the same time 
characterised by vast volcanic outbursts such as we have 
now no conception of. The parallel can be extended into 
still earlier periods of the world's history. 

An increased amount of carbon dioxide in the air not only 
warms the earth's surface, it also makes plants grow more 
luxuriantly. This was shown by careful experiments carried 
out in 1872 by the Polish botanist Godlewski. He experi- 
mented with two plants, Typha latifolia and Glyceria 
spectabilia, and he showed that they grow proportionally to 
the amount of carbon dioxide in the air until this became 
more than one per cent. The assimilation slowly increased 
until it reached a maximum when, in the case of the former 
plant, the percentage of carbon dioxide reached 6 per cent., 
and in the case of the latter, 9 per cent. On increasing the 
percentage of carbon dioxide beyond this the assimilation 
slowly decreased again. In other words, if we double the 
amount of carbon dioxide in the air, we double the rate of 
metabolism going on in the plant ; but this increased amount 
of carbon dioxide would cause the temperature of the earth's 
surface to increase 4 C, and this would increase the chemical 
changes proceeding within the body of the living plant in 
the ratio of 1 : 1.5. In other words, by merely doubling the 



250 MODERN CHEMISTRY 

amount of carbon dioxide in the air we should cause plants 
to absorb it three times as rapidly as they do at present, and 
thus grow far more luxuriantly. It is easy to understand, 
therefore, why in the Carboniferous epoch plant life flourished 
on such an immense scale. In all probability the percentage 
of carbon dioxide in the air was considerably higher than 
at present, and this, combined with the increased tempera- 
ture thus produced, caused the whole world to become a 
vast greenhouse, and produce those masses of vegetation 
whose remains to-day we use as coal. 

It has often been said that we are rapidly using up the 
valuable and irreplaceable coal buried in the earth, and 
that the time will come when it will be all exhausted. 
Nevertheless, it should not be overlooked, that, as Arrhenius 
points out, the increased amount of carbon dioxide thrown 
into the air by this means may, in the course of centuries, 
so modify the climate, so improving that of the more 
temperate regions, that the earth may ultimately be capable 
of bearing a much greater weight of harvest per acre than it 
can at present. Even at the present rate of coal consump- 
tion there is still enough to last the earth for five hundred 
years to come, and long before that time some way might 
be found for doing largely without coal. In any case, our 
descendants may safely be left to solve the problem in their 
own way. 

Carbon dioxide is easily soluble in water, dissolving to form 
a weak acid called carbonic acid, of the formula H 2 C0 3 . 
Rain washes it down from the air, and, as we have already 
pointed out, the acid water then slowly but surely eats away 
the hardest rocks, dissolving out their more soluble portions 
and leaving behind the insoluble. Perhaps of all the rocks 
occurring in Nature, chalk, limestone, and marble are the 
most soluble in water containing carbon dioxide. They are 
all modifications of the same substance, calcium carbonate, 
CaC0 3 . They are composed of the light silvery metal cal- 
cium (Ca) united with carbon and oxygen in the proportions 
indicated by the formula. Indeed, it is quite an easy matter 
to show their solubility experimentally in the laboratory. 
If we pass a current of carbon dioxide gas through lime- 



CARBON DIOXIDE 251 

water (slaked lime dissolved in water), we get at once a milky 
precipitate of calcium carbonate or chalk : 



co 2 


+ 


Ca(OH) 2 : 


= CaC0 3 


+ 


H 2 


Carbon 
Dioxide 




Lime-water 


Calcium 
Carbonate 




Water. 



If, however, we continue the stream of gas, the chalk will 
redissolve again, and the solution will again become clear. 
The reason of this is that the carbonic acid, H 2 C0 3 , which 
accumulates in the water as the gas passes through, gradually 
combines with the precipitated chalk to form a soluble com- 
pound called calcium bicarbonate, thus : 



CaC0 3 + 


H 2 C0 3 


= CaC0 3 .H 2 CO 3 


Chalk or 


Carbonic 


Calcium Bicarbonate. 


Calcium Carbonate 


Acid 





Hence water rich in carbon dioxide will dissolve rocks like 
chalk, limestone, or marble in much the same way, though 
to a less extent, that water dissolves sugar. Water which 
contains chalk dissolved in it is termed " hard." When we 
boil it for some time it becomes milky, because the heat 
decomposes the bicarbonate, driving off the C0 2 . The 
chalk is then precipitated, thus : 



CaC0 3 .H 2 C0 3 = 


= CaC0 3 


+ 


tf 2 o 


+ 


co 2 


Calcium Bicarbonate 


Calcium 




Water 




Carbon 


(Soluble) 


Carbonate 
(Insoluble) 








Dioxide. 



This fact explains why it is that kettles and boilers get 
gradually covered over with a layer of chalk when hard water 
is boiled in them. In the case of large boilers this consti- 
tutes a real danger, and greatly diminishes their life and 
effectiveness. 

The same deposition of chalk occurs, but far more slowly, if 
the water partially evaporates at ordinary temperatures. 

These facts have a great natural importance ; for many 
regions of the earth are composed almost entirely of limestone 
rocks ; and in such districts ceaselessly, century after cen- 
tury, these rocks are dissolving away under the influence of the 
carbon dioxide dissolved in rain water. This solution is not 



252 MODERN CHEMISTRY 

only proceeding on their surface, but in their interior as well. 
Every shower of rain which niters through the crevices 
of a limestone rock dissolves away some portions of it. 
Moreover, waters deep under the earth are often saturated 
with carbon dioxide under great pressure, for this gas is 
being continually evolved from underground regions. Water 
under such conditions will dissolve no less than three grams 
of chalk or limestone per litre, or about two pounds in a cubic 
yard ! 

The amount of lime which these subterranean waters, 
nay rivers is the better term, gnawing underground day and 
night, year after year, century after century, for thousands 
of years, remove in the course of time is stupendous. One 
can, therefore, scarcely wonder at the enormous size of the 
caves to be seen in limestone districts in many parts of the 
world. Indeed, such regions are often not only honey- 
combed with mighty caverns filled with rushing waters, but 
in them great rivers suddenly and without warning plunge 
underground through holes in their beds, and run deep below 
our feet 

■* Through caverns measureless to man 
Down to a sunless sea." 

Thus in Spain the Guadiana loses itself in a flat country in 
the midst of an immense savannah. In the vast limestone 
formation which extends through Carinthia, Carniola, Istria, 
Dalmatia, Albania, and Greece, the whole country is per- 
forated like a sponge by an intricate system of subterranean 
watercourses. Here may be seen the wonderful sight of 
rivers rushing forth out of the earth from one cavern and 
disappearing again into another, thus flashing into daylight 
but for a brief instant during an underground course of 
many miles. The caves of Adelsberg, Planina, and Upper 
Laibach, in Carniola, are traversed by the same river, which, 
losing its name every time it plunges into a new subterranean 
channel, is called, first the Poik, then the Unz, and finally, 
the Laibach. 

The courses of these subterranean rivers exhibit a wonder- 
ful variety of interesting underground scenery. Sometimes 



CARBON DIOXIDE 253 

they form high cataracts thundering down into mighty 
abysses ; sometimes they expand into dark and melancholy 
lakes, over whose placid waters generally not the least 
breath of air stirs, though sometimes their surfaces are rip- 
pled by wind pouring in through unseen chasms which lead 
to the surface. Where beds of hard stone oppose the flow 
of the water all that it can do is to hew out one narrow aper- 
ture, but where the rock is soft huge chambers are excavated, 
whose roofs, hundreds of feet above, are lost in gloom which 
no torch can penetrate. The water spreads widely in the 
large cavities, then, contracting its stream, it rushes through 
each defile as through a sluice. Each stream is thus a series 
of widenings and contractions, a succession of lofty halls and 
narrow tunnels often entirely rilled with swiftly flowing water, 
a fact which makes their exploration both difficult and 
dangerous. 

Among the bold explorers who have sailed down unknown 
subterranean rivers may be mentioned Dr. Schmidl. In a 
canoe he trusted himself to the dark streams of Carniola, 
near the head of the Adriatic, and was rewarded with many 
a scene of incomparable beauty.* On one journey he made 
his way up the famous cave of Planina, through which flows 
the Poik, a river at all times deep enough to float a boat. 
He reached on foot a magnificent dome about 600 feet from 
the entrance ; but here the river filled the whole width of 
the cave, and the bold adventurer had to push onwards in 
his canoe. He soon reached a portal some fifty feet high and 
twenty-five feet broad, with proportions as symmetrical as if 
made by man, and beyond this, in the darkness, heard the 
thundering roar of a mighty subterranean cataract, the herald 
of still grander scenes. Gradually the portal widened, and 
the astonished explorer suddenly saw before him a dark and 
dismal lake, about 250 feet long by 150 wide. The roof was 
so high that the light from a few torches failed to reach it, 
while the dark walls rose perpendicularly from the black 
waters, and extending upwards out of sight, presented a 
melancholy but imposing sight. Beyond the lake the cave 

* A full account of these wonderful journeys of Dr. Schmidl may 
fre found in his book " Die Hohlenkunde des Karstes," Vienna, 1854. 



254 MODERN CHEMISTRY 

was seen to divide into two arms, down which flowed two 
streams, whose waters, mingling, gave rise to the lake. 
> Pushing forward, Dr. Schmidl passed into the unknown 
regions beyond. In the left branch of the cave, into which 
he penetrated more than a mile, the boat had to be un- 
loaded more than eleven times on account of the reefs that 
obstructed its passage, while the explorer, wading through 
the water, dragged it over the shallows. Once, indeed, when 
the waters disappeared with a terrible roar under a large mass 
of rock, the boat had to be taken to pieces and rebuilt on the 
other side. 

At last they reached a gloomy hall with a lofty circular 
dome, filled by a lake 180 feet long, and forty to forty-five 
feet deep. From out of a neighbouring chasm rushed cease- 
lessly a violent cold wind. Beyond this lake they entered 
a dry chamber called by Dr. Schmidl, " The Stalactical 
Paradise." It was the first time that human eyes had ever 
beheld it. Here whole groups of stalagmitic cones, of all 
shapes and sizes, some like tiny icicles, others six feet high 
and thick as a man's waist, rose from the ground. " The 
Stalactical Paradise remained untouched," says Dr. Schmidl.* 
" I asked my companions not to break off the smallest frag- 
ment of spar as a memorial of our visit, and they all joyfully 
agreed to this. We carefully avoided trampling down any 
of its delicate ornaments, and left it with no other memorial 
than our admiration of its beauty. The nymphs of the grotto 
will no doubt have forgiven us for having intruded upon the 
sanctuary, where for countless centuries they had reigned 
in undisturbed solitude and silence." 

The other branch of the cave was also explored and extends 
for miles underground. " No description can do justice to 
the fascination of this subterranean journey," continues Dr. 
Schmidl. " In parts the roof is ornamented with coral- 
shaped draperies of snow-white stalactites, but more gener- 
ally the walls are mere black naked stone. Here and there 
streamlets gurgle down their sides, and, together with the 
melancholy trickling of single drops of water from the vault, 
alone break the silence of the dark interminable cave. The 
* Die Hohlenkunde des Karstes. 



CARBON DIOXIDE c 255 

breathless attention we bestowed on the navigation of our 
boat and on the wonders which surrounded us held us 
speechless, and we glided in silence along through the dark 
waters, that now for the first time since they began to flow 
reflected the glare of a torch/'* 

Marvellous as these caves are there are others which equal 
or even exceed them. For example, there is that wonderful 
cave of Caripe in Venezuela, which penetrates the face of a 
limestone cliff, crested with enormous flowering trees, fes- 
tooned with some magnificent tropical creepers ; straight 
like the nave of a great cathedral, for fourteen hundred feet, 
runs this magnificent arch. Out of it runs a stream, and 
along the banks of the stream, as far as the glowing tropical 
sunlight strikes in, grow wild bananas and palms. Beyond 
that the cave goes on, with subterranean streams, cascades, 
and halls, no man yet knows how far. One explorer in 1876, 
taking with him a powerful magnesium light, went in further 
than any one before ; and in one place, when he lighted up 
the magnesium, he found himself in a vast hall full 300 feet 
high, a hall far vaster than the dome of St. Paul's. And 
thus he saw what no other human being had ever seen before, 
for no ray of light had ever struck on that tremendous roof 
in all the ages since the world was made. 

" But if he found out something which he did not expect, he was 
disappointed in something which he did expect. For the Indians 
warned him of a hole in the floor (which they told him) was an 
unfathomable abyss. And lo, and behold ! when he turned the 
magnesium light upon it, the said abyss was just about eight feet 
deep. But it is no wonder that the poor Indians, with their little 
smoky torches, should make such mistakes ; no wonder, too, that 
they should be afraid to enter far into these gloomy vaults ; that 
they should believe that the souls of their ancestors live in that 
dark cave ; and that they should say that when they die they will 
go to the Guacharos, as they call the birds that fly with doleful 
screams out of the cave to feed at night, and in again at daylight 
to roost and sleep. Now, it is these very Guacharo birds which are 
the most wonderful part of the story. The Indians kill them and 
eat them for their fat, although they believe they have to do with 
evil spirits. But scientific men who have studied these birds will 
tell you that they are more wonderful than if all the Indians' fancies 

* Dr. Schmidl, loc t cit. 



256 MODERN CHEMISTRY 

about them were true. They are great birds, more than three feet 
across the wings, somewhat like owls, somewhat like cuckoos, 
somewhat like goatsuckers ; but, on the whole, unlike anything in 
the world but themselves ; and instead of feeding on moths or mice, 
they feed upon hard fruits, which they pick off the trees after the 
setting of the sun. And wise men will tell you that the making of 
such a bird as that, and giving it that peculiar way of life, and 
settling it in that cavern, and a few more caverns in that part of 
the world, and therefore the makings of caverns ready for them to live 
in, must have taken ages and ages, more than you can imagine or 
count."* 

North of the town of Adelsberg, in Austria, the stream of 
the Poik suddenly flows through a mighty doorway into the 
heart of a mountain, and gives rise to a wonderful cave, 
known as the "Grotto of Adelsberg," curious on account 
of its immense size, its innumerable white and rose-coloured 
stalactites, and the torrent which runs roaring through it. 
Certainly its vast compartments, its abysses wrapt in dark- 
ness, and the eternal echo of its rushing waters produce on 
visitors an awe-inspiring effect. One part of it, deep in the 
heart of the mountain, opens out into a stupendous hall, a 
hall so vast that its mighty roof spans 630 feet at a single 
sweep ; in its centre ascends a perfect forest of stalagmite 
columns and white needles, produced by the dripping waters 
of many ages. This cave is believed to be the original of the 
one Coleridge describes so vividly in his poem, " Kubla 
Khan " : 

" Five miles meandering with a mazy motion 
Through wood and dale the sacred river ran, 
Then reach'd the caverns measureless to man, 
And sank in tumult to a lifeless ocean." 

It is well known that in the island of Cephalonia, in Greece, 
the sea has for generations been flowing down a crack in the 
limestone, in a volume sufficient to be used for working corn- 
mills. Consequently enormous caverns must exist here 
deep underground, but which are quite unreachable by man. 

Perhaps the greatest limestone cave known in all the earth 
is the " Mammoth " cave of Kentucky. It may truly be 
called a subterranean world, having a system of lakes and 

* " Half Hours Underground " (Dalby, Isbister and Co.), p. 325. 



CARBON DIOXIDE 



257 



rivers. A network of galleries and passages, over 217 miles 
in length, cross and recross each other, going down to an 
immense and not yet ascertained depth. The main road runs 
under wonderful natural arches and domes for six miles, 
being a deserted bed of a subterranean river. In the gloom 
comes the loud ticking of the falling water as it drops 




Fig. 51. 



-The Bottomless Pit. A terrible chasm in the Mammoth Cave 
now crossed by a bridge. 



into the basins it has worn for itself in the solid rock. In 
some places are dangerous abysses. The Side Saddle Pit 
goes down a hundred feet sheer, like a quarry gaping by the 
path side. The Bottomless Pit goes down 175 feet and 
more, and is crossed by a bridge. In Gorin's Dome the floor 
far below is covered with water an acre in area. The perpen- 
dicular walls rising out of sight are draped with three 
immense stalagmitic curtains, rising one above the other. 
There is a dark sullen river slowly flowing at an immense 
depth below the ground towards an unknown destination. 



258 



MODERN CHEMISTRY 



This river, called Echo River, is in places some two hundred 
feet wide, and is navigable for three-quarters of a mile, when 
it disappears beneath an overhanging rock, and is lost to 
sight in the bowels of the earth. In this river wonderful 
blind fish are caught, fish which have lived for such ages in 
the dark that the race has lost its power of using its 




Fig, 52, — Voyaging down the sunless waters of the Echo River, 
Mammoth Cave. 

eyes ! A fleet of boats sails on its dark waters and conveys 
visitors along the whole of its navigable length. 

One distant and dangerous abyss, called the Maelstrom, 
was first explored by a boy, Prentice by name. He was let 
down by a rope into the pitch-black depths. Down he 
went, where never man had been before, swinging over the 
giddy gulf as he went. Half way down he swung into a 
waterfall which nearly put out his light. Soon he was 
through the spray, and stood on solid rock 190 feet below. 
As he came up he stopped at a niche, and, leaving the rope, 



CARBON DIOXIDE 259 

wandered off to explore a series of galleries and halls which 
opened out on to it. When he returned — oh horror ! — 
the rope had swung off the stalactite, and was dangling 
beyond his reach ! The plucky lad, however, did not faint ; 
he took the wires off his lamp, twisted them together into a 
hook, fished back the rope, and signalled aloft to hoist away ! 

The whole extent of the cave has not yet been explored. 
There exist miles and miles of unknown passages where no 
human foot has ever trod. Indeed, many of these passages 
are extremely dangerous, and the explorer runs the risk of 
being crushed by falling rock. Doubtless vast halls and 
immense galleries exist along the further unknown course of 
the subterranean river, which must run at length into the 
sea, many miles away, by subterranean passages, and so 
the known part of the cave, vast as it is, can only form a 
minute fraction of the unknown whole. 

This cave once formed a retreat for savage tribes ; for 
skeletons of men of an unknown race have been found in it 
underneath layers of stalactite. Its existence, however, 
had been forgotten for centuries, and so it came about that 
it was re-discovered only a hundred years ago by a hunter 
named Hutchins. 

The story runs that he had badly wounded a bear and was 
in hot pursuit of it when the animal disappeared in the 
dense undergrowth. Following up the trail of bloodstain? 
he found that they disappeared in a low opening almost 
hidden by a dense vegetation. He boldly entered, and to his 
astonishment found himself in this vast underground palace. 

Many caves are without any visible communication with 
the external world. Others have entrances so narrow, so 
overgrown with vegetation, that they have only been dis- 
covered by the merest chance. Sometimes workmen in a 
quarry have been suddenly surprised at meeting with a hole 
in the rock, which leads to subterranean depths. Sometimes 
the digging of wells or cellars, the boring for mines or artesian 
wells, has revealed the existence of great underground 
caverns. Undoubtedly a vast number of caves must still 
be totally unknown. Many, indeed, may be hollowed out at 
such vast depths as to be for ever inaccessible 10 man. 



260 MODERN CHEMISTRY 

Indeed, we have much evidence tending to show that under 
the earth vast caverns actually occur. When their roofs 
collapse great lakes are sometimes formed over their sites. 
It is believed that this is the origin of the wonderful Lake 




Fig, 53. — Into the Unknown. The boy Prentice exploring the Maelstrom, 
a deep abyss in the Mammoth Cave. 

Zirknitz in Carniola. It is a great depression in the ground 
which is often half full of water. At certain times of the 
year, however, its waters suddenly vanish through chasms 
under water, sucking down the fish with it. After some 
months the water again boils up from the underground 



CARBOtf DIOXIDE rtl 

depths, sometimes with such force as to hurl great rocks up 
with it, in the manner described by Coleridge in the 
lines : — 

" And from this chasm, with ceaseless turmoil seething, 
As if this earth in fast, thick pants were breathing 
A mighty fountain momently was forced ; 
Amid whose swift half-intermitted burst 
Huge fragments vaulted like rebounding hail, 
Or chaffy grain beneath the threshers' flail : 
And 'mid these dancing rocks at once and ever 
It flung up momently the sacred river." 

But the wonderful part of the story is that the fisn 
which have been sucked down into some great subter- 
ranean lake are again brought back uninjured by the 
rush of waters to the surface. Not only is this so, but 
it is said that live wild ducks who went down with 
the waters small and unfledged are brought up again 
months later when the waters boil up to the surface, and are 
then full-grown and fat, with water weeds and small fish 
in their stomachs, showing that they had plenty to feed on 
during their stay underground, besides having abundant 
quantities of air to breathe. They have, in fact, been swim- 
ming about in great dark subterranean halls. The birds 
are blind when they reach the surface from having been so 
long in utter darkness, but after a while their eyes get right, 
and they fly away like other birds. Indeed, the whole of 
this district is honeycombed with underground passages 
hollowed out by running water. Even small earthquake 
shocks can arise by the sudden collapse of the roofs of such 
caverns deep in the earth. Thus, in September, 1814, near 
Alaix, the ground emitted for twenty-four hours a sound like 
the thunder of heavy artillery ; then with a mighty crackling 
noise, it sank thirteen feet for a breadth of nearly 264 feet, 
— just the sort of effect that would be produced on the surface 
from the collapse of an underground hall. Not far from 
the town of Wagstadt, in 1827, a tract more than two acres 
in area sank in a similar way with a crash like thunder, and 
shook the land around far and wide. Indeed, if the huge 
" Salle du Calvaire " in the Adelsberg cave, whose roof spans 
630 feet, were to collapse suddenly, several acres of land on 



262 MODERN CHEMISTRY 

the surface above would be depressed some feet in exactly 
the same way. 

That the infall of enormous caverns in the earth, which 
have been hollowed out by the removal of salt, gypsum, 
calcium carbonate, and silica in vast quantities by running 
water, are the cause of earthquakes was taught by the Greek 
Philosophers over 2,400 years ago. Lucretius, in his poem 
" De Rerum Natura," thus grandly describes this idea : 

" Learn now, the cause of earthquakes ; the interior of the earth is, 
like the surface, filled with winds, caverns, lakes, precipices, stones, 
rocks, and a large number of rivers, whose impetuous waves hurry 
along in their course numerous submerged blocks. The shakings of 
the surface of the globe are occasioned by the falling in of enormous 
caverns which time has succeeded in destroying. Whole mountains 
thus sink in ruin, and the violent and sudden shock is spread far 
and wide in terrible vibrations. Thus, a chariot, the weight of which 
is not very considerable, makes all the houses near it tremble as it 
passes, and the fiery steeds, drawing behind them the iron-armed 
wheels, shake all the places round. It might well happen that an 
enormous mass of earth should fall by reason of decay into some great 
subterranean lake, and that the globe should tremble in a series of 
undulations." 

Caverns which are deserted by the rushing waters which 
formed them soon begin to be filled up again by a new agent. 
This agent is rain in which carbon dioxide is dissolved. It 
percolates down through the enormous filter of limestone 
above, and in so doing dissolves a small portion of the rock. 
The moisture, charged with calcium bicarbonate, evaporates, 
or parts with some of its free carbonic acid gas when it comes 
into contact with the air of the cave. The calcium carbonate, 
now no longer held in solution, precipitates and is set free on 
the arch of the sides of the cave, thus : 

CaC0 3 .H 2 C0 3 == CaC0 3 + CO, + H 2 

Calcium Bicarbonate Calcium Carbon Dioxide Water. 

(Soluble) Carbonate 

When a drop of water falls it leaves attached to the stone 
a small ring of the white calcium carbonate (chalk, limestone, 
marble) . This is the commencement of a stalactite. Another 
drop of water trickles down, and, trembling on this ring, 




Fig. 54. — Stalactite Columns. 



Fact page 262. 



CARBON DIOXIDE 263 

lengthens it slightly by adding to its edges another thin 
circular deposit of calcium carbonate, and then falls. Thus, 
drop following drop, minute by minute, day and night, 
summer and winter, for thousands of years, each drop deposi- 
ting part of the dissolved calcium carbonate it contains, 
builds up a number of frail tubes round which the calcareous 
deposit slowly accumulates, until mighty pendants, which 
astonish us by their vast size and ornamental structure, hang 
downwards from the roof. The water which drops from 
the stalactites deposits some more calcium carbonate on the 
floor, and in the course of ages there rises up to meet the 
descending stalactite a corresponding column from the floor. 
Ultimately the two meet and slowly coalesce to form those 
mighty snow-white pillars which hold up and support the 
roofs of the most stupendous caverns. Indeed, there are 
few sights in the world more astonishing than that of these 
subterranean palaces, with their snow-white columns, their 
innumerable pendants and decorations, pure and glistening 
like Carrara marble. But in time the caves become entirely 
filled with these growths and cease to exist. 

Often, though not always, stalactites grow extremely 
slowly. Inscriptions seventy or eighty years old appear 
covered only with a thin translucent coat. In the caves of 
Adelsberg names scratched on the walls more than six 
hundred years ago are still perfectly legible ! 

While regarding such colossal stalactites the mind cannot 
help being impressed with the innumerable procession of 
centuries required for their formation from trickling water ; 
but even these time intervals appear quite insignificant 
when compared to the previous ages required for the hollow- 
ing out of solid rock of these vast underground cavities by 
the solvent action of running water. Still beyond these 
extend fathomless ages where the limestone rocks in which 
these caves occur were being slowly deposited in the depths 
of a long vanished primeval ocean, by the accumulation of 
the innumerable skeletons of tiny sea animals, which slowly 
grew, inch by inch, into layers hundreds upon hundreds of 
feet thick, and then were slowly forced upwards by gigantic 
earth movements until the bed of the sea became dry land. 



26 i MODERN CHEMISTRY 

Nor is this the end of the vast perspective. Glimpses of 
still more distant ages loom in the distance, and the mind 
grows giddy in plunging into the never-ending abyss of 
time and of realising epochs gone and forgotten, aeons before 
man or animals appeared upon the earth at all. 



CHAPTER XII 

SILICON AND ITS COMPOUNDS 

Every one must have noted with a feeling of wonder, not 
unmixed with awe, the enormous mass of earth and rock 
which encompasses the globe on all sides. Beneath our 
feet lie miles of iron-hard rock, which extends downwards, 
layer after layer, mile after mile, until they reach the white 
hot regions of the interior and become merged in the mighty 
gleaming furnaces of the deep. In parts of the earth we find 
towering aloft, tier upon tier, in huge mountain ranges, 
millions upon millions of tons of rock and earth, which have 
been urged upwards into the air sometimes for several miles 
by mighty forces at play within the earth itself. 

This stupendous display of matter has at all times awa- 
kened the curiosity of man. Very early in his history he 
strove to obtain some answer to the problem of its constitu- 
tion. He appealed to his priests and wise men : 

" Read me the riddle of the show of things ; 
Dance of the seven stars, and stormy spray, 
Of mighty sunsets beyond mountain rings ; 
The sad level light of ebbing day along the corn." 

But they could not answer him. Their guesses were wild 
and far from the mark. And no wonder; for it took 
centuries of slow and patient labour ere man was in a position 
to attempt even to answer such questions. It was the 
chemist who first solved the problem of what earth and rock 
consist. Laboriously, step by step, with his balance and 
weights, with his tubes, beakers and filters, he toiled for 
hundreds of years upon this problem ; and ultimately he 
achieved success. He found that rocks, at least the oldest 
and most abundant kinds, are all compounds of one single 
element — the element silicon. They consist of this element 

265 



266 MODERN CHEMISTRY 

combined with oxygen, and metals like aluminium, iron, 
calcium, magnesium, sodium, potassium, and others, the 
whole forming a complex mixture of fused or chemically 
combined oxides. Yet silicon is the central element of the 
mass. It links together the other elementary atoms into 
those vast frameworks and chains of atoms which form and 
build up the gigantic skeleton of the earth's surface. No 
less than one quarter of the whole weight of the earth's 
crust consists of this element silicon. It is, therefore, in a 
combined condition, accumulated upon the earth in such 
huge masses that the mind cannot grasp their vastness ; 
and we have every reason to believe that the same constitu- 
tion must be attributed to the outer crust of the majority of 
the planets which exist in space. Indeed, it has been shown 
that in the case of our nearest neighbour, the moon, very 
probably the very same siliceous rocks which occur on the 
earth, also occur there. Thus M. Landerer found that the 
polarisation angle of the rocks forming the craters and abysses 
of the moon's surface coincided with that of certain siliceous 
rocks upon the earth, such as obsidian and vitrophyre. 
Again, meteorites which fly in from outer space upon the 
world almost invariably contain silicon, sometimes in such 
quantities as to make them almost identical in composition 
with the volcanic lavas which flow from out the earth's 
interior in volcanic eruptions. Moreover, the spectroscope 
reveals evidences of this element in the distant stars 
which are scattered through the deepest depths of space. 

The element, therefore, is a universal one. It is not con- 
fined to our earth alone, but occurs in unthinkably vast 
quantities throughout the whole universe. Indeed, the 
quantity of silicon which occurs on this earth, huge as it 
seems to us, is but an infinitesimal portion of the total quan- 
tity which occurs even in realms which are accessible to our 
telescopes. 

The substance, therefore, possesses a very considerable 
interest for us, and we shall devote this chapter to an exam- 
ination of the element and its compounds. 

Silicon belongs to the same family of elements as carbon, 
and like this element exists in several different modifications, 



SILICON AND ITS COMPOUNDS 267 

one of which — the crystalline — is hard enough to cut glass. 
Like carbon the element is extremely involatile and infus- 
ible. It requires the intense heat of the electric arc to boil, 
or even to fuse the substance. 

Only one oxide of silicon is known. Chemists call it 
silica, and have shown that its formula is Si0 2 . In other 
words, its molecules are composed of one atom of silicon 
united with two atoms of oxygen. 

Even the most unscientific reader is acquainted with this 
substance, although, perhaps, all unknown to himself, for the 
common substances, sand, flint, rock crystal, agate, quartz, 
and opal, are more or less pure forms of silicon oxide. 

Common sand, such as is found on the sea-shore, consists 
principally of tiny grains of silica. It is the debris of great 
masses of rock which once formed cliffs, bays, and headlands 
ages ago. Water acting on these rocks has in the course of 
time ground them down and washed from them all their 
soluble constituents, leaving behind the hard insoluble part, 
the silica grains, as dust upon the shore. 

The amount of sand, either loose as sea-sand, or cemented 
together and consolidated by pressure into the hard rock 
known as sandstone, which occurs upon the earth is stupen- 
dous. Vast deserts of sand occur in Asia, Africa, Australia, 
and Arabia.* 

Along every rocky coast, along the beds of oceans, and in 
rushing rivers we find it ; but in still vaster quantities does 
it occur in a fossilised condition as sandstone. Let us men- 
tion, for instance, only one layer of it, well known to geolo- 
gists, as it occurs in England alone, " the so-called New Red 
Sandstone, which, with its attendant marls, covers a vast 
tract — and that a rich and busy one — of England. From 
Hartlepool and the mouth of the Tees, down through York- 
shire and Nottinghamshire ; over the manufacturing 
districts of central England ; down the valley of the Severn ; 
past Bristol and the Somersetshire flats to Torquay in 
South Devon ; up north-westward through Shropshire and 
Cheshire ; past Liverpool and northward through Lancashire ; 

* Not all of this sand, however, is silica, some of it being merely 
powdered soil like the dust of our high roads. 



268 MODERN CHEMISTRY 

reappearing, again, north of the Lake Mountains, about 
Carlisle and the Scotch side of the Solway Firth, stretches 
the great New Red Sandstone plain, from under which 
everywhere the coal-bearing rocks rise as from a sea. . . . 
It is five thousand feet thick in places, and stretches not 
only across England, but also into Germany."* 

Whence came this enormous mass of sand ? 

It is the debris of rocks, thousand of feet thick, which 
have been worn down ages and ages ago by wind and water, 
and then were buried over by mud and earth, and finally, 
under the great pressure, have coalesced into the hard 
rock which makes such excellent building stone. 

Sandstone, however, can undergo a further change. When 
these beds of sand sink slowly beneath the ground as they 
often have done in past times, until they reach the fire and 
heat of the internal regions, then a wonderful transformation 
takes place. The sandstone under the enormous temperature 
and pressure there prevailing is transformed into a fused 
homogeneous mass, which, later arising grandly and slowly for 
thousands of years as the result of the vast earth-movements 
which are ceaselessly taking place within the globe, again 
reaches the surface. But in how different a condition ! 
It went down a formless mass of sand, it comes up a beautiful 
white rock, the hard enduring quartz, of which whole 
mountain ranges are composed. Sometimes, so deeply has 
this quartz sunk into the bowels of the earth and been 
twisted and torn by plutonic agency, that it is found impreg- 
nated with gold from the depths ; and in South Africa and 
Australia great quartz beds are now mined for the glittering 
yellow metal. Next time my reader sees a bed of quartz, 
let him not pass it by without reflecting upon its strange 
history. Think ! this hard white rock may have been once, 
ages ago, just ordinary bright yellow sand gleaming on a 
sunlit shore, washed by wave and rippled by wind. Before 
this, at a still vaster interval in the awful abyss of time, it 
formed the body of some mighty bed of rock, plutonic in 
origin, from which the sand was slowly produced by the 
action of sea, wind, and rain. Even here its history does 
* " Half Hours Underground," p. 246. 



SILICON AND ITS COMPOUNDS 269 

not end. A still remoter period dimly looms in the unfathom- 
able past, when this same silica whirled in the tumult and 
roar of the elemental flame from which our world was born. 
Before this, no man can say how long ago, it formed part 
of the great sea of ether which surrounds us on all sides and 
through which 

" The earth itself alone 

Wheels through the light and the dark 
Onwards to meet the unknown." 

The dead poet, John Davidson, once remarked of a famous 
London street : 

" Fleet Street was once a silence in the Ether, 
The carbon, iron, copper, silicon, 
Zinc, aluminium vapours, metalloids, 
Constituents of the skeleton and shell 
Of Fleet Street — of the woodwork, metalwork 
Brickwork, electric apparatus, drains, 
And printing presses, conduits, pavement, road, — 
Were at first unelemented space, 
Imponderable tension in the dark 
Consummate matter of eternity."* 

The same could be said with equal truth, of every particle 
of sand in the Universe ! The common sand about us, 
therefore, is not uninteresting — if rightly viewed. Far 
from it. Each particle of silica, each piece of quartz, each 
flintstone, or gleaming opal, can tell a story more wildly 
grand and romantic than anything that you or I, dear reader, 
have ever thought of ! 

Now let us return again to our sand. It is said that a 
handful of sand from the African desert, when examined 
with a lens, is seen to be full of rounded grains. The wind, 
dashing the particles together for ages and ages, has caused 
their angles to be worn off, and each little particle has become 
converted into a miniature pebble. Sometimes these 
sands are driven by the wind in great masses over cultivated 
lands, turning them into deserts, and bringing ruin and 
destruction with them. This has happened in every 
part of the world at some time or other. What secrets, 
what peoples, and forgotten civilisations, lie buried under 

* " Fleet Street *"d Other Poems," published by Grant Richards. 



270 



MODERN CHEMISTRY 




sand can now only be conjectured. It 
is certain that sand now reigns supreme 
in districts where, even in historical 
times, once rich meadows, gardens, and 
glad pastures existed. Ruins of old and 
forgotten cities meet one on every side, 
buried under sand, in central Asia and 
Mesopotamia. 

If silica in the form of sand has been 
one of man's most formidable enemies, 
there can be little doubt that silica in 
the form of flint stones has been one of 
his greatest friends. By means of flint 
stones he arose and gradually attained 
the mastery of the world. At some 
remote time man was an almost defence- 
less ape-like creature, far inferior in 
strength and agility to the 
Fig. 55.— Spear-head, huge and fierce animals which 
then swarmed all over the 
earth. He lived in terror of these monsters, hiding 
on tree-tops and in holes, like a wild animal. He 
fled before them much as mice flee before cats, or 
rabbits before dogs, and probably defended himself 
by hurling stones and branches of trees at them. 
One day some forgotten savage, a genius in his 
way, discovered that a fractured flint stone, if 
chipped to a suitable shape, made a most formid- 
able weapon, cutting like broken glass or sharpened 
steel. Later, he increased the force of its blow by 
fastening it into a wooden handle, when it formed 
a serviceable axe or spear. Thus he gradually 
learnt not only to make formidable flint knives, but 
also axes, spears, and even arrows tipped with 
flint, which would kill animals far swifter and more 
powerful than himself. It was only at a compara- 
tively recent period in the history of the human 
race that bronze and iron replaced the use of 
flint. Our illustrations show some flint weapons. spe?*Head 



SILICON AND ITS COMPOUNDS 



271 



These were often beautifully worked and elegant in 
form. 

As regards the origin of flint, it occurs in chalk beds, 
and appears in many cases to have replaced the chalk itself 
about a nucleus. When chalk is worn away by rain or water 




Fig. 57. — Spear-head, front and profile. 



the flint stones in it remain behind, being much more dur- 
able. If a flint stone be broken open it will usually be found 
to have grown around a fossil by some slow process of 
aggregation. 

Opals, those beautiful stones whose hidden fires, red, blue, 
and green, gleam forth from their depths, are nothing more 
than silica containing combined water. The stone bears 



272 MODERN CHEMISTRY 

minute fissures, striated with microscopic lines, which diffract 
the light and flash out rainbow tints of pure and brilliant 
hues. Some thousands of years ago the opal was known and 
prized among the civilised peoples of the earth as a valuable 
jewel. We are told that the senator Nonius was banished 
by Mark Antony for the sake of a magnificent opal set in a 
ring and valued at £20,000 of our money. By presenting 
his jewel to the triumvir he might have escaped banishment. 
He preferred to withdraw with his jewel than stay in Rome 
without it. 

One of the finest opals in the world belongs to the imperial 
jewels of Austria. It gleams magnificently with green and 
red flashes of light, and weighs no less than seventeen ounces. 
Half a million florins have been offered for it, but without 
success. 

Very fine opals have been sold at prices which rival that 
asked for diamonds of equal size. Black opals also exist, 
and are highly valued. They allow the red fire of the ruby 
to flash out gorgeously against the darkness of the stone. 
Besides opals we get precious stones, such as amethyst, 
cairngorm, jaspers, and chalcedonies, which are also com- 
posed of silica, but which are, at the same time, coloured 
with a trace of some impurity, usually the oxide of a metal. 

A description of all the varieties of silica used for orna- 
mental purposes would occupy too much space, but this 
account would not be complete without a few words on rock 
crystal. 

Many varieties of this beautiful mineral are found. For 
example, there is violet rock crystal or amethyst, yellow 
rock crystal or "false topaz," black rock crystal or 
" morion," and brown rock crystal or " smoke quartz." The 
beautiful limpid and colourless kinds are often called 
Bristol or Irish diamonds. They occur in the Alps, and, 
indeed, in all regions where a great deal of quartz rock is 
found. They are much used for making j ewellery and optical 
instruments. The use of quartz instead of glass for lenses 
is especially valuable ; for being harder than glass it will 
not easily scratch or lose its polish. Its use in spectroscopes 
depends upon the fact that it is extremely transparent 



SILICON AND ITS COMPOUNDS 273 

to ultraviolet light. The substance has other valuable 
properties, but we cannot discuss them here. 

Small rock crystals have little value, but high prices are 
paid for large ones. Consequently they are much sought 
for by the chamois hunters and goatherders of the Alps. 
Nearly a century and a half ago a quartz cave was found 
at Zinken which gave twenty tons of beautiful rock crystal, 
which sold for over 300,000 dollars. One single crystal 
weighed 800 lbs. In 1867, some tourists, descending from 
the solitudes of the Galenstock, saw some dark spots in a 
band of white quartz which traversed the face of a mighty 
precipitous cliff. The guide, Peter Sulzer, of Guttannen, 
declared them to be cavities which would certainly contain 
rock crystal. No search was made at the time, but some 
weeks after Sulzer and his son revisited the place, and climbed 
up the perilous cliff until the holes were reached. They 
found that they led inwards into a dark cavity from which 
they took out some pieces of black rock crystal with the 
curved handles of their alpenstocks. Next year, accom- 
panied by a few friends from Guttannen, to whom they had 
told the secret, they made a determined effort to force their 
way into the cave. Boldly they climbed the cliff and reached 
the cavity. Here they had to maintain themselves on a 
small ledge, only a few inches wide, overhanging a nearly 
vertical cliff, and at the same time use the hammer and 
other implements for breaking up the rock. 

The weather was very bad. Every now and then a 
fierce gust of wind threatened to tear them from their 
clinging place and hurl them down upon the glacier deep 
below. Hail and rain stiffened their limbs, and to make 
matters worse, darkness came on and found them still at 
work. They passed a dreadful night closely huddled to- 
gether on a narrow ledge before the cavity. At last morning 
broke and found them wet to the skin, with their teeth 
chattering with cold. They resumed their labours, and at 
length widened the entrance sufficiently to allow them to 
penetrate into a cave which plunged into the mountain for 
a considerable depth. It was filled nearly to its roof with 
a mound of fallen rock and sand ; but here and there. 



274 



MODERN CHEMISTRY 



imbedded in the rubbish, gleamed jet-black morions, which 
showed that their toil had not been in vain. Originally 
the crystals had grown on the sides and roof. Here they 
must have hung for many thousands of years until, at some 
unknown time, the 
concussion of an earth- 
quake, or perhaps their 
own weight, precipi- 
tated them with a 
crash upon the floor. 
More than a thousand 
large crystals were 
found in the cave, 
many of them weigh- 
ing from fifty pounds 
to more than three 
hundredweight. The 
first explorers collected 
about a ton of crystals, 
and brought them to 
the village. In a short 
time the greatest ex- 
citement reigned here, 
and the whole able- 
bodied population of 
Guttannen, armed with 
hammers, spades, 
baskets, and ropes, 
poured out in a long 
stream to the cave, 
and began to carry 
away the remainder. 
Meanwhile, the report 
had spread that the 
Canton of Uri, on whose land the cave was situated, was about 
to stop their proceedings. So the men worked day and night 
with feverish haste, and in the space of a week had stripped it 
of its treasures. The stones were conveyed over the glaciers, 
and over the roads beyond the reach of the authorities. 




Fig. 58. — Discovery of the Rock Crystal 
Cave of the Galenstock by the guide 
Peter Sulzer and his son in 1867. 






SILICON AND ITS COMPOUNDS 275 

One of the party fell into a crevice with a crystal of a hundred 
pounds upon his back. He managed to get out, but lost 
his prize in the depths. The seven finest specimens were 
bought for 8,000 francs by the Berne Museum, and are still 
exhibited as a magnificent group. 

The largest crystal, called the " King," is thirty- two inches 
high and three feet in circumference, and weighs 255 pounds. 
Next comes the " Grandfather " of inferior height but 
superior girth, and weighs 276 pounds. Most of the other 
fine crystals were sold to various museums and private 
collections for six or seven francs a pound. So that Sulzer's 
discovery brought much wealth to the little village. 

The oxy-hydrogen blowpipe flame has a temperature 
(2,000° C.) just over the melting point of silica. Consequently, 
quartz can be melted in this to a colourless glass-like 
mass, which can be made to boil in the electric furnace. 
This fused quartz forms a truly wonderful glass. Since the 
year 1900 colourless vessels, tubes, and other pieces of 
chemical apparatus have been manufactured, which look 
exactly like ordinary glass but have this astonishing pro- 
perty : they can be heated to a white heat and suddenly 
plunged under water. Glass under such circumstances 
would fly into a thousand fragments. These quartz vessels 
are, however, not affected in the least by such treatment ! 
The reason of this is that this quartz glass has the 
lowest co-efficient of expansion for heat of any known 
substance, the mean co-efficient between 0° C. and 
1,000° C. being only 0.0000007. Consequently, when 
suddenly cooled, great internal strains, such as shatter 
suddenly cooled glass, are not set up. For the same 
reason the application of a sudden and intense heat to 
quartz vessels will not cause them to break. We all know, 
as a matter of painful experience, how easy it is to crack 
articles of ordinary glass by heating them too suddenly. 
For the chemist these articles are invaluable, because these 
quartz-glass vessels are inert to most operations; they 
may be heated hundreds of degrees higher than ordinary 
glass without melting, and, as we have already related, are 
extremely transparent to ultra-violet light. They are 



276 MODERN CHEMISTRY 

at present, however, expensive articles, although doubtless 
the future progress of science will eliminate this disadvantage. 

If quartz be melted in a blowpipe, and the end of an arrow 
be dipped into it and be suddenly shot off from a bow, the 
arrow flying through the air will draw out after it a long, 
extremely fine thread of quartz fibre ; such fibres, on account 
of their strength and fineness, are much used for suspending 
the moving parts of electrical measuring instruments. I 
suppose, too, that they could be woven into wonderful gar- 
ments which would have the warmth and lustre of silk, 
combined with far greater strength and durability. Such 
silica cloth could be heated to a high temperature without 
damage, behaving in some respects something like asbestos. 
However, I have not heard of any experiments which have 
been made in this direction. 

Silica, Si0 2 , is under ordinary circumstances insoluble 
in water. Yet deep down in the earth water exists in a 
tremendously heated and compressed condition, and under 
such circumstances it acquires the power of dissolving 
silica from the rocks, forming silicic acid : 



Si0 2 


4 


2H 2 


s- 


Si(OH) 4 


Silica in Rocks 




Comoressed and 
Heated Water 




Silicic Acid. 



When such water comes to the surface where the pressure 
and temperature is low, it cannot hold so much silicic acid 
in solution. Consequently, some of it is deposited at the 
mouth of the spring, as a thick jelly, which afterwards passes 
into a hard white sinter. This especially occurs in volcanic 
regions. Many geysers are surrounded by mounds of silica. 
The most celebrated and perhaps the most beautiful of all 
these springs is the Great Geyser of Iceland. During the 
lapse of centuries this has formed for itself a base of silica no 
less than fifty-two feet in width, which serves as the wall 
of a funnel-like hole seventy-five feet deep, from the bottom 
of which rise the water and steam. When a discharge 
is to take place the water surface swells up in foamy heaps, 
and the ground trembles and roars with a stifled sound. 
Clouds of steam arise and shroud the basin. Suddenly an 



SILICON AND ITS COMPOUNDS 2JJ 

enormous jet of steam and boiling water leap out with a 
mighty crash, and like a pillar of glittering snow shoots up 
ioo feet or more into the air. A second and a third jet 
rapidly follow. Then the water subsides in the basin, and 
for hours, sometimes for days, no fresh eruption takes place. 
Leaning over the edge of the hole, whence such a storm of 
foam and water has just issued, and looking at the tranquil 
blue surface of the water below, it is hard to believe in the 
sudden transformation that has taken place. The deposits 
of siliceous matter left by the spring have already erected a 
conical hillock around it, and sooner or later the increased 
pressure of the water thus enclosed will cause them to open 
a fresh outlet beyond the present one. But hot siliceous 
waters have produced even more wonderful effects in New 
Zealand. About the centre of the Northern Island thermal 
springs, mud-fountains, and geysers, rise in more than a 
thousand places. For a distance of more than a mile the 
lake of Tampo boils and smokes, heated by subterranean 
fires. A river runs from this lake down to the sea, and 
from its valley squirt so large a number of boiling water 
jets that in one spot alone seventy-six have been counted, 
rising to various heights, and playing alternately, as if 
governed by a mysterious rhythm in their successive ap- 
pearances and disappearances.* Further on all is activity. 
" Liquid columns gleam all at once in the sun, and white 
cascades fall from terrace to terrace towards the river. 
Each instant the landscape changes, and fresh voices take 
a part in the marvellous concert of gushing springs." t 

In this region once existed what has been termed the 
eighth wonder of the world, namely, the fairy Lake of Roto- 
mahana. All around it bubbled and spouted hot siliceous 
springs. Eighty- two feet above the lake stood a deep crater- 
like basin, from the centre of which water and steam spouted 
out. The basin was composed of a dazzling white layer of 
silica which had been deposited by the clear waters which 
filled it. The water in this glittering basin was of a wonder- 
ful blue shade, rendered more beautiful by the reflection 

* Reclus, " The Earth," p. 564. 
f Von Hochstetter, " Neu Zeeland." 



278 MODERN CHEMISTRY 

of rolling clouds of steam. The liquid overflowing from 
the basin ran into a similar pool, likewise covered with white 
silica, and falling thence from terrace to terrace reached the 
level of the lake. In this way a series of glittering steps of 
wondrous beauty and grace were formed, over which the 
water spread in thin sheets, and then fell in cascades. Some- 
times the whole body of liquid in the upper basin was 
suddenly upheaved in a stupendous column with a roar 
like thunder, the whole presenting a scene of incom- 
parable grandeur. Sad to relate, a volcanic eruption has 
within recent years swept away the whole fairy-like 
scene. 

Similar terraces exist at the Mammoth Springs, Yellow- 
stone Park, in the United States. 

Two forms of silicic acid appear to exist : one, which 
dissolves in water to form a " colloidal " solution, something 
like a solution of glue or gelatine ; the other is insoluble 
in water and forms a jelly. 

When silica, Si0 2 , is fused with caustic soda, NaOH, or 
better, with sodium carbonate, Na 2 C0 3 , an " Orthosilicate " 
of formula Si (ONa) 4 is formed. This looks like glass, and 
is soluble in water. For this reason it is called " water 
glass," and is used as a medium for preserving eggs, and for 
making artificial stone. If acid is added to the solution, 
orthosilicic acid is produced thus : 

+ 4 NaCl 

Salt 



Si (ONa) 4 + 


4HC1 


= 


Si (OH) 4 


Sodium Orthosilicate 


Hydrochloric 




Orthosilicic Acid 


(Water Glass) 


Acid 







The silicic acid remains in solution, and may be separated 
from the salt by placing the solution in a drum covered with 
parchment paper, and then floating the whole on water. The 
salt diffuses through the parchment, while the silicic acid 
remains behind. On evaporating the liquid in vacuo the 
solution of silicic acid is obtained as a viscid fluid, which, 
on raising the temperature, separates out as a jelly. This 
silica jelly is insoluble in water, and appears to have the 
constitution 0=Si (OH) 2 . It is termed " Metasilicic acid." 
On further drying water is gradually expelled, and finally 



SILICON AND ITS COMPOUNDS 279 

a mass is left which, on strongly heating, yields a white 
powder, which is pure silica or sand, Si0 2 . 

The innumerable carbon compounds which enter into the 
structure of living animals and plants are capable of forming 
similar jellies and colloidal solutions. Living matter, in fact, 
is of an essentially gelatinous nature. Perhaps this is one of 
the reasons why silica enters so largely into the constitution of 
some forms of living matter. Thus many plants, such as 
grasses, straws, bamboos, and other straw-like growths, 
store up in their harder parts quite large amounts of silica, 
which makes them stiff and hard and able to stand upright. 
They nourish themselves by means of the roots with solu- 
tions containing dissolved silica, and this is how the substance 
gets into them. Sea animals and plants are especially prone 
to assimilate silica. 

Many of the lower organisms which exist in the ocean 
take silica out from the finely suspended clay floating in the 
water, and from it build up their skeletons. Tiny diatoms 
have formed in some parts of the world, by the slow accumu- 
lation of their siliceous skeletons, beds of " tripoli " or 
" polishing earth " or " kieselguhr," which within recent 
years have been much used in manufacturing dynamite. 
A truly wonderful structure these minute skeletons have, 
as the merest glance through a microscope will show. Other 
siliceous organisms are tiny animals called " Radiolaria." 
These creatures build up chambered structures of silica, 
sometimes of singular beauty and complexity. Some 
sponges also secrete considerable quantities of silica in the 
form of spicules ; of these the beautiful Venus's Flower 
Basket is a notable example. 

At some hot springs (especially in the geyser district of 
the Yellowstone Park in America) extensive deposits of 
silica are said to be caused by vegetation — principally algae 
— which possess the power of causing silicic acid dissolved 
in water to be thrown down as a stiff gelatinous substance 
in many varied forms. On the death of the plant the jelly- 
like mass, which consists of the siliceous filaments of the algae, 
and their slimy envelope, loses part of its water, becomes 
cheese-like in consistency, and finally hardens into stone. 



,6o 



MODERN CHEMISTRY 



We thus see that silicon — like the 
element carbon of the same chemical 
group — can enter into the constitu- 
tion of living matter. Indeed, in 
past ages, when the seas were 
hotter and more closely in contact 
with the hot siliceous rocks, it pro- 
bably played a much greater part in 
living matter than it does to-da}^. So 
also, for the matter of that, may 
sulphur, arsenic, phosphorus, and 
other elements which now occur in 
protoplasm only in the most trivial 
traces. Probably the structure of 
living matter has, like all other things 
we are acquainted with — for example, 
the atmosphere — undergone a con- 
tinuous process of evolution (and is 
still undergoing it) with the changing 
external conditions.* 

We have already mentioned that 
the primitive rocks are for the most 
part mixtures of complex compounds 
termed " silicates," which are unions 
of silica with metallic oxides. Mr. 
F. W. Clark, from the mean of 830 

analyses of typical samples from the older or primitive 
part of the earth, deduced the following as its average 
composition : f 




Fig. 60. — Euplectella 
Suberea Sponge. 
Many sea organisms take 
up silica from the 
sea-water and with 
it build themselves 
wonderful skeletons. 



■* The whole problem is fully discussed in the author's work 
" Researches on the Affinities of the Elements," in which it is 
shown that out of the four elements, carbon, nitrogen, oxygen, 
and hydrogen, which principally enter into the constitution of 
living matter, no single one is chemically differentiated by any 
properties from other elements. Every property possessed by them 
is shared to a greater or less extent by other elements as well. Con- 
sequently these other elements could presumably under other condi- 
tions replace them in living matter, and thus generate living forms 
which perhaps could flourish at quite high temperatures. 
| " Geikie's Geology," p. 87. 



SILICON AND ITS COMPOUNDS 



281 



Silica (Si0 2 ) 










• 59.71 


Alumina (A1 2 0,) . . 










• i5-4i 


Ferric oxide (Fe 2 3 ) 










. 2.63 


Ferrous oxide (FeO) 










• 3.52 


Lime (CaO) 










. 4.90 


Magnesia (MgO) . . 










. 4.36 


Potash (K,0) 










. 2.80 


Soda (Na 2 0) 










• 3-55 


Water (H 2 0) 










. 1.52 


Titanic acid (TiO a ) 










. 0.60 


Phosphoric acid (P 2 5 ) 




• «-• • 


. 0.22 




99.22 



Nevertheless, the different minerals which go to compose 
these rocks vary somewhat widely in composition. Accord- 
ing to Clark all the silicates may be classed as salts of five 
silicic acids, viz. : 



Si(OH) 4 


OSi(OH) 2 


H 6 Si 8 7 


H 2 Si 2 5 


H 4 Si 3 


Orthosilicie 


Meta silicic 


Diorthosilieic 


Dimetasilicic 


Trisilicic 


Acid 


Acid 


Acid 


Acid 


Acid. 



The subject is, however, much too complex to be discussed 
in a work of a popular nature. We may, however, give the 
formulae which have been proposed for some naturally 
occurring minerals : 

HO. y OH 

>S< 
HO OH 

Orthosilicie Acid. 



(Mg, Fe)< >S< >(Mg, Fe) 

Olivine. 



. Si0 4 5= KH 2 
Al • Si0 4 = Al 
* Si0 4 ss Al 

Putash Mica or Muscovite. 



Be< >Si< >Be 





Beryl. 




. Si0 4 = 


Al 


) Al • Si0 4 = 


Al 


' Si0 4 = 


Al 


Xenolite. 




. OH 




Al • Si0 4 = H, 




• Si0 4 = Al 




Kaoliu or China Cby. 





28a MODERN CHEMISTRY 

O O 

. O . || II 

Al • O • Si — O — Si — O — Si — OK 
' O • 

Orth <clase Felspar. 

However, since the molecular weights of these minerals are 
not known with certainty, their true constitution may, in- 
deed, be very different from that given above. Indeed, some 
of the natural silicates appear so complex that no simple 
formula at all can be given to them. Although hardly any- 
thing is known of their true internal constitution, the reader 
must not come to the conclusion that the subj ect is dry and 
uninteresting. Far from it ; for we are here on the verge of 
a mysterious unknown chemical world, which science has at 
present no methods of attacking and penetrating. We can 
truly believe, however, that, when in the coming centuries 
men have succeeded in devising methods for penetrating 
it, discoveries as wonderful and astonishing will be made in 
this realm of silicon compounds as anything appertaining 
to that of the carbon compounds, whose spread and develop- 
ment forms a veritable romance in the history of the nine- 
teenth century. We may come to regard the seem- 
ingly inert rocks around us as the scene of changes as complex 
and wonderful as anything now going on in organic nature 
in such abundance. Certainly the microscope reveals in 
these rocks a very wonderful structure. How very remark- 
able, for example, are the structures revealed in the accom- 
panying photographs of real rocks as seen through the 
microscope. These show us that the rocks are, indeed, far 
from the formless shapeless masses that they are commonly 
supposed to be among non-scientific readers. Some of them 
are full of tiny holes filled with liquid gas, often enclosing 
tiny crystals. Others are filled with invisible cavities and 
passages. We may, indeed, well ask: if in their coarse 
physical features the siliceous rocks reveal such a wonderful 
complexity of structure, what wonders would be revealed 
in them if we could only penetrate down to the minute atomic 
world below, and see the motions and groupings of their tiny 



SILICON AND ITS COMPOUNDS 



283 



molecules, and the long chains of vibrating atoms which 
compose them ? Were we endowed with senses a million 
times more delicate than those we possess the silent rocks 
would surely awake and emit the thunder of countless billions 
of atoms clashing, rushing, swinging ceaselessly. We should 
perceive the rocks to be the seat of vast forces, whose very 
magnitude would appal and amaze us. All notion of their 
inertness would vanish with our ignorance. The phrase 




Fig. 61. — Wonderful Microscopic Structure of Siliceous Rocks. Many of 
these rocks are aggregations of crystals of different sizes, sometimes 
beautifully coloured. Besides these crystals millions of tiny cavities 
occur, often filled with liquids and containing still minuter crystals. 

(Illustration from " Geikie's Textbook of Geology," Vol. I., p. 151, Figs. 14 
and 15. Published by Macmillan & Co. in 1903. Fourth Edition.) 

" dead as a stone " would become meaningless, for we 
should see that all rocks, all stones, are the theatres of mighty 
cosmic processes, scarce dreamt of by us, ceaselessly going 
forward night and day, summer and winter, for century after 
century, on a stupendous scale, until the mighty results so 
abundant on every side are produced. The whole fabric 
of the world itself, from its outer surface to its deepest 
depths, is in a state of never ceasing flux. 

Let us illustrate this by an example. Every one has seen 
great mountains of hard rock, towering aloft into the 
sky, motionless, firm, silent, as if placed there for all eternity. 
Yet this apparent stability and immobility is quite false. 
The mightiest masses of rock are slowly crumbling, and at last 



284 MODERN CHEMISTRY 

will pass to dust. In time,the hardest granite cliffs soften, fall, 
and disappear. Basalt, one of the hardest of rocks, becomes in 
time comparatively soft, and like granite, loses all its strength 
and rigidity. In Cornwall and in the Channel Islands, as 
well as in many other parts of the world, the granite has 
become so soft and rotten that it can be dug with a spade to 
the depth of several yards. If we go to the geologists they can 
tell of rocks thousands upon thousands of feet thick, piled 
tier upon tier aloft for miles, which have in time rotted and 
been washed into the sea. They can furnish you with 
examples of " denudation," as they call the process, which 
at first sight take our breath away, and cause us to ask : 
Is it possible ? Is it credible ? Hear, for example, what 
the geologists say regarding Snowdon : * 

" Any one who saw that noble peak of Snowdon . . . leaping 
high into the air, dominating all the country round, at least upon 
three sides, would have the right at first sight, on hearing of earth- 
quake faults and upheavals, to say the peak of Snowdon has been 
upheaved to its present height above and out of the lower lands 
around. But when he came to examine sections, he would find his 
reasonable guess utterly wrong. Snowdon is no swelling up of the 
earth's crust. . . . Snowdon is a mere insignificant boss, left hanging 
on one slope of what was once an enormous trough, or valley, of 
strata far older than itself. By restoring these strata, in the direc- 
tion of the angles, in which they crop out, and vanish at the surface, 
it is found that to the north-west — the direction of Menai Straits — 
they must have once risen to a height of at least six or seven thousand 
feet ; and more, by restoring them, especially the ash-bed of Snowdon, 
towards the south-east — which can be done by the guidance of cer- 
tain patches of it left on other hills — it is found that south of Ffes- 
tiniog . . . the south side of the trough must have sloped to a 
height of from fifteen to twenty thousand feet. . . . The fact is 
certain, that off the surface of Wales, south of Ffestiniog, a mass of 
solid rock as high as the Andes has been worn down and carried 
bodily away .... If I am asked whither is all that enormous mass 
of rock — millions of tons — gone ? Where is it now ? I know not. 
But if I dared to hazard a guess, I should say it went to make the 
New Red Sandstones of England." 

This is the epitome of the process. First hard rock which, 

when exposed to the air, changes on its surface ; then 

a process of dry rot or decay sets in and renders its outer parts 

soft; then it crumbles and is washed away down into the 

* " Half Hours Underground," p. 273. 



SILICON AND ITS COMPOUNDS 285 

valleys below by the rain and running waters, and this 
goes on year after year until all is washed away. 

What is the reason ? let me explain, starting at the very 
beginning. You must all know that the rocks, at least the 
primitive ones, are but the frozen remains of a vast sea of 
liquid white-hot siliceous matter. Ages ago the world hung 
in space a liquid white-hot globule, surrounded on all sides 
with clouds of steam and rushing gas. It was at this period 
that the immense masses of siliceous rocks which now cover 
the earth were formed. Consequently their composition 
corresponds to chemical repose or equilibrium at a white 
heat. The carbon dioxide gas now stored up in the earth, 
then, as we have seen, floated free in the atmosphere, over 
this sea of white-hot molten siliceous rock. It could do this 
under such conditions ; but it cannot rest thus at lower 
temperatures. At lower temperatures the system is not in 
a state of chemical repose or equilibrium, for although at a 
white heat silica will decompose carbonates and drive out 
their carbon dioxide into the air, yet at ordinary tempera- 
tures the reverse is the change which takes place. The 
carbon dioxide will slowly decompose silicates, setting free 
silica or sand, and forming carbonates. The rocks, therefore, 
are not at ordinary temperatures in a state of chemical 
equilibrium with the carbon dioxide of the air, but are con- 
tinually, century by century, absorbing it and decomposing. 
Hence, on a mighty scale there is continually going forward 
a change in the composition of the earth's crust. More 
and more carbon in the form of calcium and magnesium car- 
bonate is being heaped up in the interior of the earth, while 
the silicon oxide which previously was combined with those 
metals is being steadily set free in the form of sand and clay. 
We may express the whole transformation, qualitatively, by 
means of the following scheme : 

Fe 2 3 . MgO. CaO. Al a 3 . ioSi0 2 + 2C0 2 = CaC0 3 

Approximate Composition of Primitive Carbon Calcium 

R^ck Di-xide Carbonate. 

+ MgC0 8 + A1 2 3 . 2 Si0 2 + 8Si0 2 + Fe 2 3 

Magnesium Clay £and Iron 

Uib.-iiate 0*ide. 



286 MODERN CHEMISTRY 

In consequence of the gigantic geological changes which 
have been going on steadily for almost unthinkably vast 
intervals of time, the large amounts of carbon dioxide which 
once floated in the air are now almost all withdrawn into the 
earth and stored up in the limestones and dolomites in the 
form of calcium and magnesium carbonates. Once the 
amount of carbon dioxide which floated in the atmos- 
phere occupied a volume more than 800 times the whole 
volume of the present atmosphere. Now, in consequence of 
these geological changes, it is reduced to the minute per- 
centage of 0.03. That is only three parts in ten thousand of 
air ! Professor Ostwald believes that in the course of time 
every scrap of carbon dioxide will be withdrawn from the 
atmosphere, and that there will then not be enough of this gas 
to supply all the carbon of the living world, as it does at 
present, and that consequently living matter will have to 
alter its composition or perish. This time, however, is very 
far distant. At the present time very probably volcanoes 
alone throw more carbon dioxide yearly into the air than 
is taken up by rocks. We discussed this point in our chapter 
on carbon dioxide. We can, however, forcibly realise 
to what extent this gas is stored up in the ground by 
supposing that some awful giant from some other star were 
to soak the whole earth with a strong acid, such as nitric 
or hydrochloric, then this acid acting upon the limestones 
and carbonates of the earth would set free all the carbon 
dioxide stored up in the chalk with violent effervescence, 
and the gas would come pouring out of the ground in such 
quantities as to blow whole continents into the air and form 
a layer of gas around the earth some 700 or 800 times the pre- 
sent volume of the atmosphere. Indeed, the carbon dioxide 
thus evolved would exert such a pressure that under its own 
weight it would liquefy and form regular seas ! 

Silica at a high temperature also acts as a strong acid, 
and the same effect as regards the evolution of carbon dioxide 
would be produced by merely heating the earth to a white 
heat. The silica would then completely decompose the 
carbonates, evolving the gas, and restoring the earth to its 
ancient state. Perhaps, indeed, the carbon dioxide now 



SILICON AND ITS COMPOUNDS 28 



evolved in such quantities through volcanoes takes its origin 
in this way. 

Without the aid of water, however, the carbon dioxide 
could never have effected these mighty changes. To water 
no rock is perfectly impervious. By it, probably, none are 
wholly unaffected. Water, especially when it contains car- 
bonic acid dissolved in it, soaks into the rocks, dissolves out 
their soluble parts, and leaves behind the insoluble. The 
most insoluble constituent of most rocks is silica, Si0 2 . 
Another very insoluble constituent is aluminium silicate or 
clay, Al 2 3 .2Si0 2 .2H 2 0. Still a third insoluble constituent 
is magnesium silicate or serpentine, MgO.Si0 2 .H 2 0. Hence, 
when water and carbon dioxide have acted for ages on rocks, 
we find that all their material is dissolved away and washed 
into the sea except these insoluble residues which are left 
behind. This explains the common occurrence of sand and 
clay all over the world in almost every region. It explains, 
too, why vast masses of serpentine rocks are found in certain 
parts of the world. They represent all that is left of still 
older rocks. The fine china clay or Kaolin is caused by the 
decomposition of granite rocks, and especially felspar, thus : 



2 O.A1 2 0,.6Si0 2 + 


CO, 


= K.CO, 


Felspar 


Carbon 
Dioxide 


Potassium 
CarbDnate. 


A1 2 3 2Si0 2 


+ 


4Si02 


Kaolin or China 
Clay 




Sand. 



The clay is washed away from the sand and forms in beds. 
Ages later the clay thus formed consolidates to slates and 
other clayey rocks. 

Thus we see how chemical science not only underlies the 
science of geology, but the study of a single one of its ele- 
ments, the element silicon, introduces us to some of the 
mightiest geological problems that have ever exercised the 
human mind. 

Glass and Pottery are the earliest products of man's 
chemical industry. 

More than 6,000 years ago the plains of Mesopotamia were 



288 MODERN CHEMISTRY 

covered with great cities built of brick and paved with 
asphalt. The capital of the Asiatic world, the wonder-city of 
Babylon, covered an area of nearly 200 square miles, and 
was surrounded by huge brick walls 342 feet high and ninety 
feet thick ! In its centre towered mighty brick temples 
nearly 600 feet into the air. Even to-day the ruins of such 
structures, the Birs Nimroud, and the Babil, are 235 and 
130 feet high respectively. We may well ask what European 
monument is there which, after crumbling in upon itself, 
would reach 130 feet after thirty centuries of ruin ? Similar 
buildings existed at as early a period in Egypt. 

Besides brick, earthenware vessels and beautifully 
coloured tiles were manufactured thousands of years ago 
both by the Egyptians and the Babylonians. Glass, too, was 
known probably 6,000 years ago. The temple of Belus in 
Egypt, a giant structure 600 feet high, was built sixty cen- 
turies ago out of bricks coloured with glass enamel. The 
invention of glass itself must have followed soon after. We 
find sculptures of glass blowers on the reliefs of the tomb 
of the king, Beni-Hassan, who lived 1800 years before Christ. 
In 1700 B.C. we find beautiful blue and white glass vases. 
We know that Sesostris, in the year 1643 B.C., had cast a 
monument of green glass. In later times the seat of the 
old glass industry was Alexandria and the towns Tyre and 
Sidon. Here, centuries before our era, gleamed and glowed 
great glass furnaces, while glass merchants grew wealthy 
and built themselves houses and palaces. All this, however, 
has long passed away ; Tyre and Sidon are now marked only 
by a few ruins rising among the wretched huts of villagers. 
Alexandria still remains, however, a centre of commercial 
industry. 

From the East the knowledge of glass and earthenware 
passed to Greece and Rome, and thence spread with the 
Roman legions all over Europe. 

The modern glass industry is enormous. In the United 
States alone over 160,000,000 glass bottles are made yearly, 
besides vast amounts of window glass, glass globlets, pitchers, 
and ornaments. In Europe even greater quantities are 
made, 



SILICON AND ITS COMPOUNDS 289 

The primary materials for making glass are : Sand or silica 
(Si0 2 ) ; lime (CaO), lead oxide, or baryta; sodium carbonate 
(Na 2 C0 3 ), or potassium carbonate, or sodium sulphate. 

These materials are mixed together in the proportions 
suitable for the kind of glass required to be made — for there 
are very many different kinds of glass — and are then fused 
in a furnace. 

Sometimes there are added to the glass for special purposes 
small amounts of oxides of metals, such as cobalt, copper, 
iron, tin, zinc, etc., as well as other stuffs, such as borates, 
nitrates, phosphates, carbon, etc. 

Glass, in fact, is a complex mixture of silicates, to which 
no simple chemical formula can be given. 

Glass may be coloured beautifully red by adding cuprous 
oxide or gold to it. Manganese oxide colours it red or violet. 
Cobalt oxide gives it a wonderful blue colour, and was used 
for this purpose thousands of years ago by the ancient 
Egyptians. The addition of lead oxide gives it a brilliance 
like diamond, and such " paste " is now largely used for 
imitation jewellery. 

The reader should visit a large glass manufactory and 
see glass in the making. Here he will see huge furnaces 
with their glowing lakes of molten glass ; and wonderful 
mechanisms for pressing the glass with ceaseless celerity 
into a multitude of different objects, such as jampots, 
saltcellars, vases, and other things as well. 

Then there are the mixing machines, and a machine for 
picking up the glass, blowing it into a bottle, and dropping it 
into a receiver at the rate of six hundred an hour ! 

That the clay on a river's bank retained foot impressions, 
etc., which in the sun soon hardened and retained their form, 
must have been observed by the most primitive peoples. 
They formed, therefore, rude vessels out of this river clay 
and dried them in the sun ; but since such sun-dried vessels 
soon fell to pieces when moistened with water, the great 
advance was made of heating them afterwards in a furnace. 
Under such treatment they hardened and retained their 
form when brought into contact with water. As we have 
seen already, pure clay is a silicate of aluminium, whose 

T 



2Q0 MODERN CHEMISTRY 

formula is Al 2 3 .2Si0 2 .2H 2 0. Impure clays vary con- 
siderably in composition, usually containing much iron oxide, 
which gives them their dark red colour, as well as free silica, 
magnesium, and calcium carbonates. Plastic clays will take 
up 78 per cent, of water and form a dough-like mass, which 
can be squeezed or worked into any form we wish. When 
small quantities of oxides of different metals are added to 
the clay and the whole strongly heated in a furnace it hardens 
to our ordinary earthenware. The addition of quartz or 
felspar to pure white clay cements it on intense heating into 
white porcelain. 









CHAPTER XIII 

SULPHUR AND ITS COMPOUNDS 

The familiar yellow sulphur is an element which is very 
widely distributed. In every volcanic region of the earth 
we find sulphurous exhalations arising, especially from 
craters and solfataros, which impregnate the earth around 
them with this element, although seldom in quantities 
large enough to be remunerative. Very large amounts 
of sulphur occur in Sicily, where the element has been mined 
for centuries. The numerous sulphur pits of that island are 
situated chiefly in the southern districts over an area of 150 
geographical miles. They occur in crevices and hollows, 
where the sulphur is, no doubt, the product of volcanic 
actions which took place in tertiary times. In such districts, 
rising up through countless clefts and fumaroles from the 
mysterious furnaces of the deep, we find the poisonous 
gases hydrogen sulphide, H 2 S (sulphuretted hydrogen), 
and sulphur dioxide, S0 2 . Mingling together, they mutually 
decompose each other, producing sulphur, thus : 

2H 2 S + S0 2 = 3S + 2H 2 

Hydrogen Sulphide Sulphur Dioxide Sulphur Water. 

The oxygen of the air also decomposes the sulphuretted 
hydrogen slowly, thus : 

2H 2 S + 2 = 2S + 2H 2 

Hydrogen Sulphide Oxygen Sulphur Water. 

As a result of such actions the liberated sulphur condenses 
in the gypsum and clay grounds of the superficial strata. 
Some authorities believe, however, that it is produced in 
part directly from the gypsum (CaS0 4 ) as the result of 
bacterial action. 

291 



292 MODERN CHEMISTRY 



. 



Formerly, when sulphur was used solely for makin; 
gunpowder, its production was relatively insignificant ; but 
at the present time it is used for a great many other purposes 
— such as making sulphuric acid, bleaching, as a disinfectant, 
for making vulcanite, mosaic gold, and other commodities 
— and consequently its price has risen considerably, being 
now practically the chief article of Sicilian exportation. 
Girgenti is the most important sulphur exporting town in 
South Sicily ; yet its dirty miserable streets and its 19,000 
inhabitants form a sad contrast to the wealth and luxury of 
ancient Agrigentum, within whose lofty walls a population 
of 800,000 once lived. All the neighbouring sulphur pits 
send their produce to the port of Girgenti, and on all the roads 
one meets with long files of mules and asses loaded with 
sacks of sulphur. 

It was the grape disease — against which sulphur was 
found to be the onl> effective remedy — that gave a new 
impulse to the sulphur industry by raising the price to about 
three times its old value. As soon as the grape disease 
became a national calamity for the chief wine-producing 
countries, the merchants of Girgenti at once bought 
up large tracts of sulphur lands and thus made their 
fortunes. 

In order to extract the element from the sulphur-rich 
earth the Sicilians now burn it in circular kilns about thirty 
feet in diameter and ten feet high. First of all straw is intro- 
duced ; then on this are laid large blocks of sulphur-rich 
earth, with air spaces between ; over this come smaller 
stones, and finally the top is covered with a layer of the 
burnt-out earth from former operations. On lighting the 
straw the sulphur in the lower layer of stone burns and the 
heat thus generated melts out the sulphur in the earth above. 
It pours down and collects as a yellow compact mass in a 
receptacle under the kiln. The product thus obtained is 
very impure, and it is now usually purified by distilling from 
large iron retorts into brickwork chambers. Here it con- 
denses as a light yellow powder sold as " Flowers of Sulphur." 
After a time the chamber becomes heated and the sulphur 
then collects as a liquid, which is drawn off and cast into 






SULPHUR AND ITS COMPOUNDS 293 

conical wooden moulds, and is known as roll sulphur or 
brimstone. 

The sulphur earth usually contains thirteen to thirty per 
cent, of sulphur and occurs in great beds fifteen to ninety feet 
thick. Some of the longest excavations in them are so 
narrow that a man can only with difficulty pass ; then they 
expand into high vaults, whose roofs gleam and glisten with 
beautiful crystals of celestine and gypsum. An oppressive 
heat reigns in these pits, and the workmen are on this 
account quite naked. Their dark skins, sprinkled with dirt 
and yellow sulphur dust, give them a strange and savage 
appearance. 

The majority of the people of Girgenti work in the sulphur 
pits ; a few are engaged in cultivating the beautiful gardens 
and fields which roll from the foot of the town to the sea, and 
cover the site where once the busy streets and stately palaces 
of the ancient city of Agrigentum rose from the shore to the 
terraced hills above, which are still crowned with the ruins 
of her colossal temples. Sicily yields yearly nearly 100,000 
tons of sulphur. 

Perhaps the most remarkable event in the history of the 
Sicilian sulphur fields occurred in 1787 in the celebrated pit 
of Sommatino, which is situated on the precipitous right 
bank of the Salso Valley. Some workmen accidentally set 
it alight, and the fire raged incessantly for two years, filling 
the pit with deadly sulphur dioxide gas and causing the 
complete abandonment of the mine. The owners gave up 
their property as lost and seemed menaced with utter ruin ; 
but one day, quite suddenly, the mountain side burst asunder, 
dense fumes and yellow smoke poured out of the falling earth, 
and from the midst of it a mighty stream of molten sulphur 
rushed forth and buried itself in the neighbouring river. 
This phenomenon was caused by Nature performing on an im- 
mense scale an operation similar to that by which sulphur 
is extracted from the ore. The heat of the burning sulphur 
in the mine melted it in the rock above and caused the 
liquid to collect in the cavities of the mountain side to such 
an extent that this split asunder, and a mass of pure sulphur, 
amounting to more than 40,000 tons, was cast forth. By 



294 MODERN CHEMISTRY 

this lucky event the owners of the pit were suddenly raised 
from threatened ruin to a condition of affluence. 

Italy also yields a very large amount of sulphur. In 1900 
no less than 400,000 tons of sulphur were obtained from her 
mines. Enormous beds of sulphur occur in the United States 
of America. Quite recently these have begun to be worked 
by a new process with very great success. The sulphur is 
melted out by means of superheated steam, and the molten 
sulphur is then pumped up from wells to the surface. 

Remote Japan — that region of earthquakes and volcanoes 
— has within recent years entered the field as a sulphur 
supplying land ; and, indeed, enormous supplies of sulphur, 
often in an almost pure state, are met with. Kampfer in his 
" History of Japan " mentioned that it is the produce of 
a small island called " Iwogasima " or the " Sulphur Island." 
" It is not above a hundred years since the natives first ven- 
tured to explore that desert spot, which, from the smoke 
rising from its surface, was previously supposed to be the 
abode of demons. At length, a bold adventurer obtained 
leave to visit the dreaded island. He chose fifty resolute 
men to accompany him on his hazardous expedition, and on 
landing, instead of the fiends he expected to encounter, he 
found a volcanic soil, covered in many parts with thick 
deposits of sulphur, and emitting dense clouds of smoke from 
countless fumaroles. Ever since that time the island yields 
a considerable revenue to the Prince of Satzuma." An 
interesting account of sulphur mining in the Island of Etrofu, 
near Japan, has recently been given by Mr. Crawford.* He 
says, " On the upper end of a little island in the North 
Pacific Ocean, half way between the most northern point 
of the mainland of Japan and the Peninsula of Kamchatka . . . 
are located what are now supposed to be the most valuable 
deposits of sulphur in the world. There are three volcanic 
mountains, about 2,800 feet in height, of almost pure sulphur, 
and the vapours pouring from the summit of each are adding 
to the deposits day by day. The island is away from all 
the lines of regular communication, and so far north that 

* Cassier's Magazine, November, 1900, April, 1901, Vol. 19, p. 311. 
Quoted by kind permission of the publisher. 




Girgenti, in Sicily. 



Although a small town of only 19,000 inhabitants, yet a large proportion of Sicilian sulphur is exported 
from it. In the foreground are seen the ruins of the ancient Agrigentium, which once held a population of 
800,000 within its lofty walls. 




Fig. 63. — At the top of Sulphur Mountains near Japan, 2,800 feet above sea level. 

Notice the suffocating gases and vapours rising up through the soil. The whole of the ground seen in the 
illustration is solid, almost pure, yellow sulphur, of unknown depth. (From C ussier' s Magazine, Vol. 19.) 

Face page 294. 



SULPHUR AND ITS COMPOUNDS 295 



it is completely ice-bound from November to May." In iJ 
the island was explored by American and Japanese engineers, 
and it was discovered that the immense sulphur cones were 
located about two miles from the sea-coast, within easy reach 
of an excellent harbour called Moyors Bay. It is estimated 
that over 1,500,000 tons of almost pure sulphur are here lying 
on the ground, and this is now actively mined in the summer 
months (in winter the ground is covered with twenty-five 
feet of snow), and transferred to the bay by an overhead 
wire rope transmission plant. It seems almost incredible 
when we read of mountains of pure sulphur, which have only 
to be dug away like earth, and carted in a pure condition 
to industrial centres ! Yet this seems to be the case here. 
" The writer's first view of the deposits," continues Mr. 
Crawford, " showed clouds of steam pouring from several 
places near the summits of the hills, and far down along 
the sides glistened immense patches of dull yellow, which were 
occasionally lost to sight as a fickle breeze wafted the vapours 
in such a way that the brighter yellow sulphur of the summit 
could be seen. ... On climbing to the top, the hills were 
found to consist of almost pure sulphur, inasmuch as diggings 
at every conceivable place brought up the yellow crystals. 
The sulphurous vapours which poured from subterranean 
depths were suffocating, and, instead of issuing from only 
a few places as it seemed when viewed from a distance, the 
whole cap of each hill was honeycombed, and each outlet was 
continually adding to the stock, day by day, as the vapours 
were condensed." Naturally the sharp acid fumes in the air 
destroy the vegetation of the island, and it is practically 
an utterly barren waste, except along the shore. 

Most minerals when once removed by mining operations 
are irreplaceable, and the deposit is thus gradually exhausted ; 
but this is not so with sulphur. Very often the deposits 
are renewed again, and that within fairly short intervals of 
time. This is especially the case on the floors of the craters 
of partially extinguished volcanoes. Thus, to give one case, 
the mixture of sulphur and gravel on the floor of the old crater 
at Puzzuoli, near Naples, is dug up and distilled to extract 
sulphur. The gravel is then returned to its original place, 



296 MODERN CHEMISTRY 

and in about thirty years is again so rich in sulphur as to 
serve for the same purpose once more ! 

Leopold von Buch states that : " The crater of the Peak of 
Teneriffe is now but an immense Solfatara. The sulphurous 
vapours which escape from every part of the vast cauldron, 
decomposing the rock, convert it into clay, and cover it in 
many places with beautiful crystals of sulphur. By this 
constant chemical action, the soil towards the centre of the 
crater has been rendered so soft that in many cases great 
caution is necessary to avoid sinking into the yielding mass, 
which has a temperature higher than that of boiling water." 
In Armenia the sulphur is precipitated in thick crusts on 
the vast inaccessible cliffs surrounding the volcano Alaghez. 
The people of the neighbourhood have a peculiar method of 
collecting this mineral. They fire at masses of it which 
cluster on the sides with musket balls and pick up the frag- 
ments thus detached ! 

In Java, near Patuka, is a circular lake over a quarter of a 
mile in diameter, surrounded with a luxuriant vegetation 
and filled with clear water of a bright yellow tint caused by 
the reflection of a vast sheet of sulphur which covers its 
bottom. In the lake occurs an island composed entirely of 
sulphur ! It is well known that wonderful volcanic caves 
occur in various parts of the world. They have in most 
cases been formed by the passage of vast volumes of steam 
and vapour through red-hot molten rock. Thus a famous 
cave on Etna, the " Fossa della Palomba," consists of a 
series of dark cavities, penetrating downwards by a series 
of precipices, which are descended by ladders. The vaults 
terminate in a great gallery ninety feet long, beyond which 
lies still a passage never yet visited. The volcanic caves 
in the Island of St. Michael, in the Azores, are still vaster. 
Their entrance is through a narrow crack which expands 
suddenly into an enormous hall, whose distant roof is hidden 
in darkness even in the strongest torchlight. In one spot 
an opening in the floor shows that the lava, here but a foot 
thick, forms the roof of a huge cave underneath, into which 
even the boldest explorer has never yet ventured ; but the 
noise of stones dropped into the abyss prove it to be of con- 






SULPHUR AND ITS COMPOUNDS 297 

siderable size. Other caves of great height open out from 
the first one. The famous Surt-shellier cave in Iceland is a 
similar cavity of vast extent. "It has been very appro- 
priately named after Surt, the prince of darkness and fire of 
the ancient Scandinavian mythology ; for this gloomy deity 
could not possibly have chosen a fitter residence than its 
vast and dismal halls, once glowing with subterranean fires, 
and now the seat of perpetual darkness." 

Naturally, after what we have said about the occurrence 
of sulphur in volcanic districts, it will not surprise the reader 
when we tell him that many of these subterranean cavities 
are incrusted with sulphur and filled with poisonous sulphur- 
ous gases. Thus the mountain Budoshegg in Transylvania 
possesses such caves. On advancing a few steps into one 
the air becomes sharp and suffocating, and the feet begin to 
feel a warmth which gradually increases to an intolerable 
heat. Still further on the lights are extinguished, and a 
speedy retirement is necessary. Imprudent explorers have 
been known to pay for their curiosity with their lives. 

In the island of Milo likewise are sulphur caves which 
yield annually some 500 tons of pure sulphur. Still a visit 
is not without danger owing to the suffocating fumes which 
issue from crevices in their floors and sides. 

Seldom, indeed, have such extraordinary efforts been made 
to collect sulphur above the regions of perpetual snow as 
were made by Cortez during that wonderful campaign 
which ended in the overthrow of the empire of Montezuma.* 
Being in want of powder he sent a body of men under 
Francisco Montano, a cavalier of resolute courage, to collect 
sulphur from the smoking throat of Popocatapetl, which 
towers, covered with a dazzling mantle of everlasting snow, 
to the height of 17,852 feet above the sea level. First they 
struggled through the lower regions, which were clothed 
with dense forests so thickly matted as to be almost impene- 
trable. Higher up they struck a black surface of glazed 
volcanic sand and lava, the overflow from some recent erup- 
tion. Its broken fragments, arrested in its boiling progress 
in a thousand fantastic forms, offered the greatest difficulties 
* Prescott's "History of Mexico." 



298 MODERN CHEMISTRY 

to their advance. Finally they came to the limit of perpetual 
snow, where fresh dangers presented themselves. The 
slippery ice gave them an insecure footing, and a false step 
might precipitate them into the frozen chasms that yawned 
around. Respiration became difficult in the thin air of these 
lofty regions ; every movement was attended with sharp pains 
in the head and limbs, accompanied with breathlessness. 
At last they reached the edge of the crater — a vast irregular 
ellipse more than a league in circumference. At the bottom 
a lurid flame burnt gloomily. From the depths rolled up 
clouds of sulphurous steam, which, cooling as it rose, con- 
densed on the walls of the cavity. But who was to venture 
into the depths for sulphur ? All shrank from the awful risk. 
So lots were cast and it fell on Montano himself to descend 
in a basket into the terrible abyss. Down he went, with his 
frail vessel swinging in the air as he went, until he reached 
the depth of 400 feet. Here he found sulphur in abundance, 
and filling the basket he was hauled into safety again ; but 
it was not until the dangerous journey was repeated many 
times that the bold soldier had collected sulphur enough for 
the wants of the army. 

The preceding cases show us that almost wherever we get 
volcanic action on a large scale, there we also find sulphur. 
The element is an almost constant concomitant of volcanic 
action. Judging from this one would certainly say that if 
we could, like the hero of one of Mr. Wells' novels, travel to 
the moon in a flying machine, we would certainly find there 
enormous deposits of sulphur, probably immensely exceeding 
any which occur on our earth. For the surface of the moon 
exhibits signs of having been in the past the theatre of the 
most tremendous volcanic action, compared to which the 
greatest displays which have occurred on our planet in 
historical times are absolutely insignificant. There our tele- 
scopes reveal to us the presence of mighty craters a hundred 
miles and more across, craters so vast that their huge precipi- 
tous walls, rising perpendicularly for thousands of feet, would 
actually be out of sight in the distance if we were standing 
in the middle of the crater floor ! Almost every square yard 
of our satellite's surface is pitted with extinct fumaroles and 




Fig. 64. — In the Cra s ter of Popocatapetl. This giant crater, which towers 
into the air to the height of nearly 3 \ miles, contains a large amount of 
sulphur. It was the source from which Cortez obtained the sulphur 
required for the gunpowder of the army which was to overthrow the 
empire of Montezuma. 

(Illustration from " Land, Sea, and Sky," published by 
Ward, Lock & Co. in 1882.) 

Face page 29S. 






SULPHUR AND ITS COMPOUNDS 299 



volcanic openings, through which, doubtless, clouds of suffo- 
cating vapours once rose and deposited sulphur in every 
crack and cranny. No doubt, as in the case of terrestrial 
volcanoes, the walls of the mighty precipices surrounding 
these great craters are incrusted with sulphur, the undis- 
turbed growth of ages, and in their centres the mounds and 
cones we see arising are perhaps impregnated with pure 
sulphur. Our telescopes, indeed, afford us indirect evidence 
of the presence of this element, for it is found that many parts 
of these volcanic beds are snow-white. It is believed that here 
the sulphurous vapours and steam arising up through them 
have decomposed the volcanic rock in much the same way 
that the same agents have decomposed the rock in the bed 
of the crater of Teneriffe, and have turned them into white 
beds of kaolin or china clay. A mineral prospector arriving 
from the earth would undoubtedly have a splendid time 
wandering about the silent mountains and dead valleys of 
our satellite and noting its mineral riches, which, in these 
airless and waterless deserts, have lain undisturbed and 
uncorroded for immense geological ages. 

What we should see in these dead lunar craters may be 
surmised from what actually can be seen in active craters on 
the earth. Thus the crater of Vesuvius, as it appeared in 
1867, is thus described by an eye-witness : — 

We stood on the summit (of Vesuvius) at last — it had taken an 
hour and fifteen minutes to make the trip. What we saw there was 
simply a circular crater — a circular ditch if you please — about two 
hundred feet deep, and four or five hundred feet wide, whose inner 
wall was about half a mile in circumference. In the centre of the 
great circus ring thus formed was a torn and ragged upheaval a 
hundred feet high, all snowed over with a sulphur crust of many a 
brilliant and beautiful colour, and the ditch enclosed this like the 
moat of a castle, or surrounded it as a little river does a little island, 
if the simile is better. The sulphur coating of that island was gaudy 
in the extreme — all mingled together in the richest confusion were 
red, blue, brown, black, yellow, white, — I do not know that there 
was a colour, or shade of a colour, or combination of colours, unrepre- 
sented — and when the sun burst through the morning mists and 
fired this tinted magnificence, it topped imperial Vesuvius like a 
jewelled crown. The crater itself — the ditch — was not so variegated 
in colouring, but yet in its softness, richness, and unpretentious 
elegance, it was more charming, more fascinating to the eye. . . . 



300 MODERN CHEMISTRY 

Beautiful ? One could stand and look down upon it for a week 
without getting tired of it. It had the semblance of a pleasant 
meadow, whose slender grasses and whose velvety mosses were frosted 
with a shining dust, and tinted with a pale green that deepened 
gradually to the darkest hue of the orange leaf, and deepened yet 
again into brown, then faded into orange, then into the brightest 
gold, and culminated in the delicate pink of a new-blown rose. Where 
portions of the meadow had sunk, and where other portions had been 
broken up like an ice-floe, the cavernous openings of the one, and the 
ragged, upturned edges exposed by the other, were hung with a lace- 
work of soft tinted crystals of sulphur, that changed their deformities 
into quaint shapes and figures that were full of grace and beauty. 
The walls of the ditch were brilliant with yellow banks of sulphur, 
and with lava and pumice stones of many colours."* 

Magnify this picture a hundredfold, and you will obtain a 
good idea of the gorgeous scenery to be seen within the giant 
lunar craters, where there exists no rain nor air to dim the 
vivid colouring of the sublimed minerals. All remains as 
gorgeous and as fresh and as vivid as on the very day, millions 
of years ago, when they came up from the fiery deeps below, 
amidst torrents of choking and hot vapours. 

The reader must not be led to suppose from what we have 
said in the preceding pages that free sulphur is solely the 
product of volcanic action, for it is also the product of the 
life-processes of certain curious bacteria which occur in 
innumerable millions in some waters and moist earths. These 
bacteria absorb so much sulphur that ten to twenty-five 
per cent, of their body is composed of this element. Some 
of them contain the sulphur in their bodies as tiny granules ; 
from such bacteria vast quantities of sulphur have been 
deposited over different parts of Europe, especially in Urbino 
and Reggio in Italy, Radoboy in Croatia, and Girgenti in 
Sicily. In the same way that we acquire energy and 
warmth from the slow oxidation of carbon in our bodies to 
carbon dioxide, so do these strange creatures acquire their 
vital energy by the oxidation of sulphur to sulphuric acid.f 
"* Sulphur occurs also in our own bodies, and in living matter 
generally — though naturally to a much smaller extent than 
in true sulphur organisms. The evil smelling gases given orl 

• M The Innocents Abroad," by Mark Twain, 
t Professor W. O. Ostwald. 






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SULPHUR AND ITS COMPOUNDS 301 

from a putrefying egg and from decaying animal matter are 
largely due to the evolution of gases rich in sulphur. Hair, 
wool, and the acids of the bile contain especially large 
quantities of it. The sulphur, however, appears to be but 
loosely combined in living matter, and its true function is 
unknown. It may be, however, that in earlier ages, and 
in the most primitive organisms, this element played a 
much more prominent part than it does now, and that the 
small quantities which now remain in ordinary living matter 
are the evolutionary relics of a time when it was far more 
abundant ; for surely with the widely different thermal con- 
ditions which prevailed on the earth in early times the com- 
position of living matter also must have been different, and 
its present composition is merely the end result of ages 
of evolution. 

In the earth, too, sulphur is stored in enormous quantities, 
not free but combined with metals, forming compounds 
termed sulphides. 

Ordinary sulphur is a yellow solid, insoluble in water, 
which melts at a low temperature (114-119 C.) and burns 
with a blue flame, emitting a poisonous suffocating gas 
called sulphur dioxide. It is this gas which causes the 
acid sharpness and suffocating properties of the air in 
volcanic crevices. Like carbon, the element sulphur exists 
in several different forms; for example there are two 
entirely different crystalline varieties known. These 
facts teach us that ordinary sulphur is not the simple 
substance that we at first sight imagined. It certainly has 
a molecule containing a large number of atoms, and it is 
the different types of molecules thus produced that give 
rise to the different modifications. 

If sulphur is gradually heated it melts to a limpid, straw- 
yellow, mobile fluid. As the temperature rises the fluid 
thickens and darkens in colour, until at 180 C. it is almost 
black and so viscid that it can be scarcely poured out of the 
vessel. This is, indeed, a curious change, the cause of which 
is at present unknown. On heating to a still higher tem- 
perature the liquid becomes less viscid, and if it be then 
suddenly cooled by pouring into water we get another 



302 MODERN CHEMISTRY 

surprise. The sulphur has changed into a dark coloured 
elastic mass utterly unlike ordinary sulphur. Indeed, it 
somewhat resembles indiarubber and can be drawn into long 
threads, which when released from tension spring back again. 
This modification is known as plastic sulphur. It is, however, 
unstable, for after a time it becomes hard and passes into 
ordinary yellow rhombic sulphur. 

Very many important and interesting sulphur compounds 
are known, among which may be mentioned sulphuretted 
hydrogen or hydrogen sulphide, H 2 S. This is a remarkable 
colourless gas which has a horrible odour similar to that of 
rotten eggs — which, indeed, owe their smell to it. The gas is 
colourless, very soluble in water, and burns with a faint 
blue flame. 

Since the gas occurs as a product of the decay of animal 
matter it often accumulates in stagnant sewers and drains. 
Now the substance not only has a very evil smell, but it is 
horribly poisonous. No gas, with the possible exception of 
prussic acid vapour, kills with such alarming suddenness. 
A man entering an atmosphere of almost pure hydrogen 
sulphide suddenly and without any warning loses conscious- 
ness, and falls dead on the floor. Even when inhaled in small 
quantities it is rapidly fatal. Thus, 0.2 per cent, in the air 
kills animals in a minute or two, and 0.07 per cent, in an hour 
or two. Thus it comes about that workmen entering 
stagnant sewers have time after time been struck down by it 
and have lost their lives. A man has been known to descend 
into such a place and vanish. After a time the men above, 
hearing nothing of him, go down to see what has happened, 
reach a layer of the gas suddenly, and without even uttering 
a warning sound, fall senseless and perish. Indeed, the 
columns of our daily papers will often record sad cases where 
rescuer after rescuer has been struck down in this way. 

In salt mines very often large amounts are evolved from 
the earth (probably by the action of acid waters on sulphides) 
and many fatalities have occurred. In volcanic regions the 
gas is often evolved from underground. 

A very surprising outburst of hydrogen sulphide gas from 
underground occurred in 1896 during the building of Smith's 









SULPHUR AND ITS COMPOUNDS 303 

Point Lighthouse in Chesapeake Bay. While workmen 
were excavating the foundations of the lighthouse, working 
in compressed air in an iron caisson some fifteen feet below 
the level of the sea, the deadly gas suddenly began to stream 
into the workchamber from the sandy bottom of the sea. 

Thirty-five men were in the caisson at the time. They 
smelt the horrible stench arisng from beneath them, and 
looking up, perceived that the candles stuck along the iron 
walls were burning with peculiar green flames. The gas 
began to work. Man after man began to stagger, giddy, with 
eyes almost blinded and a horrible burning sensation in the 
throat. A rush was made for safety, and all succeeded in 
escaping ; but the men suffered terribly from the after 
effects ; all night they lay sleepless and moaning, and in the 
morning only a very few could open their eyes at all, while 
light itself caused them the greatest pain. Bags were fitted 
over their heads, and they had to be led out to their meals. 
Meanwhile doctors arrived, and an examination of the 
caisson showed that the workmen had struck a vein of 
sulphuretted hydrogen gas. Indeed, when the air lock 
of the caisson was opened, the stench, even at a steamer's 
length from the caisson, became quite intolerable. For 
three days the force lay idle. Repeated attempts were 
made to rid the caisson of gas by flooding, but with- 
out success, and consequently all the work was at a 
standstill. On the fourth day the manager called for 
volunteers to go down the air shaft, and fourteen men bravely 
stepped forward " to see the work through," in spite of the 
appalling spectacle of thirty-five comrades moaning in their 
bunks, with blinded eyes and burning throats. Descending, 
they found the flow of gas much less rapid, and so they 
started working with feverish energy, expecting every moment 
to feel the gas gripping them. Every half-hour another 
shift of men came on, and by nightfall the lighthouse was 
within an inch or so of its final resting-place. The last shift 
had the worst experience of all. It was headed by an old 
caisson man, Griffin by name, a man of exceptional strength 
and endurance, who had borne the record air pressure of 
seventy-five pounds while sinking the famous Long Island 



304 MODERN CHEMISTRY 






gas tunnel. It was well the men had this leader, for just as 
they were getting ready to leave the caisson the gas burst 
forth again with a roar from the sea-bottom, and in an instant 
filled the interior of the caisson. Then a terrible scene 
ensued. Flinging down their tools, all made a wild rush for 
safety ; but the air shaft was narrow, and only one man 
could get up at a time. So they fought and struggled around 
the man-hole, pulling down by main force every man who 
succeeded in reaching the ladder rounds. Now the gas 
blinded them, and they began to stagger apart, swearing, 
praying, and beating with their naked fists on the iron walls, 
imploring to be let out. Finally the majority sank senseless 
upon the floor, only a few of the stronger ones escaping by 
scrambling up the ladder ; Griffin remained below and sig- 
nalled for a rope. At last it came down, and he groped for 
the nearest workman, fastened it round his waist, and sent 
him up. Painfully he collected the unconscious men beneath 
the air shaft, and when the rope came down again, sent 
them one after another aloft in the same way. Last of all 
came a powerfully built Irishman named Howard, and 
although Griffin was by this time half blinded by the gas 
and only semi-conscious, he managed to get him aloft. Now 
an unexpected difficulty occurred. The Irishman's body 
wedged fast in the eighteen-inch door of the air lock, and the 
men outside could not pull him through. So Griffin feebly 
and painfully climbed, as if in a bad dream, the thirty feet of 
ladder and pushed and pulled until the lifeless body went 
through. He attempted to follow, but his numbed fingers 
slipping on the steel rim, he slid back into the death-trap 
below, and relapsed into a semi-unconscious condition. The 
rope was lowered once more, and Griffin, rousing himself 
by a supreme mental effort from the torpor into which he 
was rapidly sinking under the influence of the gas, managed 
to fasten the rope under his arms, and was finally dragged 
up. Griffin was blind for six weeks, while two of the men 
had to go to a hospital and were months in recovering. 
Another man went insane, while four caisson men came out 
of the work with a painful malady known as " the bends," 
which often attacks those who work under great air-pressure. 






SULPHUR AND ITS COMPOUNDS 305 

The reader can easily prepare some of the gas and study 
its properties by merely pouring sulphuric acid on ferrous 
sulphide : 



FeS 


+ 


H 2 S0 4 


sss 


FeS0 4 


+ 


H 2 S 


Ferrous 




Sulphuric 




Ferrous 




Sulphuretted 


Sulphide 




Acid 




Sulphate 




Hydrogen, 



Another interesting gaseous compound of sulphur is 
sulphur dioxide, S0 2 . This also is colourless and invisible, 
with a strong sharp suffocating smell. Unlike sulphuretted 
hydrogen the gas will not burn, and extinguishes a burning 
light. It is very soluble in water, and the solution possesses 
bleaching properties. Goods like silk and straw, which 
would be damaged seriously by the application of bleaching 
powder, are often treated with the substance. The gas may 
be produced by heating strong sulphuric acid with copper 
in a flask, when it is evolved in a copious stream ; the reaction 
is complex but is usually represented by the equation : 

Cu + 2H 2 S0 4 = CuS0 4 + S0 2 + 2H 2 

Copper Sulphuric Copper Sulphur Water. 

Acid Sulphate Dioxide 

Sulphur dioxide is also produced when sulphur burns in 
the air, thus : 

s + o 2 - so 2 

Sulphur Oxygen Sulphur Dioxide. 

As burning sulphur is used for disinfecting purposes, I 
suppose all my readers, even the non-chemical ones, have at 
some time or other smelt the peculiar suffocating odour of 
the gas when generated in this way. It is evolved in very 
large quantities from volcanoes, and is so heavy that it 
pours along the ground, like water, filling up hollows, and 
suffocating animals found in them. Even men have been 
overwhelmed by it when it pours from the top of the crater 
in eruptions. A well-known historical case is that of the 
elder Pliny, who was destroyed by the vapours which poured 
along the ground from the eruption of Vesuvius in a.d. 79, 
the same eruption that buried Pompeii and Herculaneum. 
Pliny was the admiral of the Roman fleet stationed at 
Misenum, and being informed that a great danger threatened 
v 



306 MODERN CHEMISTRY 

the inhabitants around the Bay of Naples, because Vesuvius, 
a previously inactive mountain, had broken into eruption, 
and was throwing out ashes and stones in every direction, 
he embarked with his ships of war and set sail to bring help 
to the people along the coast ; but as he approached the 
coast hot ashes began to fall upon the ship, as well as pumice 
and other stones blackened and scorched by fire. Then 
suddenly the sea shoaled, and the masses ejected by the erup- 
tion rendered the coast inaccessible. The steersman advised 
him to sail back, but Pliny, animated with all the valour 
of a Roman gentleman, pushed onwards into danger, saying 
to the man, " Fortune favours the bold ; steer towards the 
villa of Pomponianus." Here he landed, calmed his friends' 
fears, composedly dined and bathed — although the air was 
black with falling stones and ashes — and then retired to sleep. 
But now high columns of flame burst forth from Vesuvius, 
and lighted up the darkness and terrors of the night ; the 
earth continually reeled and trembled, while the thunders 
of volcanic explosions reverberated around. Soon the 
ashes and stones were falling so thickly that the house was 
in danger of being buried, so waking Pliny, the whole party 
bound cushions upon their heads in order to protect them- 
selves from the falling ashes and stones, and then with lighted 
torches in their hands they hurried to the shore in order to 
embark on the war-galleys. "Everywhere else day was 
shining, but here it was the blackest night, for the sun's rays 
were completely shut out by the falling dust and smoke 
clouds. But the sea was too wild and boisterous to embark. 
So Pliny lay down on a carpet and asked for cold water, 
which he repeatedly drank. But now there came rolling 
down from the mountains flames and black sulphurous 
vapours. All fled. Pliny rose, and leaning on two slaves, 
tried to walk, but immediately sank down again, suffocated 
by the dense smoke which rolled about him." Thus 
perished in his sixty-sixth year one of the greatest scientists 
and noblest characters of ancient Rome, the author of the 
first general description of the world. He undoubtedly 
succumbed to a mixture of sulphur dioxide and carbon dioxide 
gases which were pouring along the ground. If he had stood 



SULPHUR AND ITS COMPOUNDS 307 

the whole time like the rest of the party, and not lain on a 
carpet, there is little doubt that he would have escaped with 
his life. 

Enormous volumes of sulphur dioxide and carbon dioxide 
were evolved during the great volcanic outburst in Iceland, in 
1783. The ground split open, and such huge volumes of gas, 
accompanied by torrents of lava, were poured forth, that no 
less than 9,000 men, and over a quarter of a million of oxen, 
horses, and sheep were suffocated ! ^ 

Sulphuric acid, H 2 S0 4 , also known as " oil of vitriol," is 
one of the best known and most valuable compounds of 
sulphur. It is manufactured on a large scale by oxidising 
sulphur dioxide. 



CHAPTER XIV 

THE PHOSPHORUS GROUP OF ELEMENTS 

In the year 1674 the alchemist Brand, of Hamburg, made a 
remarkable discovery, which, a century and a half later, 
led to the development of a great industry employing 
many thousands of workmen all over the world, and put into 
the hand of every one the means of obtaining fire cheaply 
and easily. The story runs that he was heating in a retort 
evaporated urine and white sand in the hope of preparing 
a liquid supposed to have the power of turning silver into 
gold ; while applying an intense heat he suddenly saw vapours 
arising from the retort and condensing on the cooler parts of 
the apparatus in the form of a waxy, translucent solid. On 
investigating this new body, which we now know is the 
element phosphorus, he found that it possessed the astonish- 
ing property of gleaming in the dark with a ghostly glimmer 
like pale moonlight, and when rubbed along a wall left behind 
it a luminous trail. Moreover, the substance was exceedingly 
inflammable. A very slight degree of heat — the warmth of 
the hand was sufficient — caused it to melt, catch fire, and 
blaze furiously, emitting dense white fumes. If the experi- 
menter were unfortunate enough to get any of the blazing 
liquid on his skin, it inflicted dangerous and deep wounds, 
which often took months to heal. 

Naturally the discovery of this strange element awakened 
a wonder and interest in the contemporary world very 
similar to that caused within our own times by the discovery 
of radium, and consequently it was possible for the chemist 
Krafft to make a tour of Europe and exhibit phosphorus as 
one of the wonders of Nature to various crowned heads. 
Among others our own King, Charles II., and the fair ladies 
of his court inspected it with lively astonishment. Even 

308 






THE PHOSPHORUS GROUP OF ELEMENTS 309 

after the lapse of more than two centuries, during which 
time phosphorus has changed from a substance almost as 
rare and costly as gold into a common and familiar body, 
we still view with wonder its cold gleaming light. Light 
without fire ! Strange as the phenomenon seems it is but 
the outward manifestation of still more marvellous things. 
Think : in order to produce visible light, the tiny sub-atoms 
which build up the phosphorus atoms must whirl round their 
molecular orbits ten thousand billion times in a single second ! 
" What an incredible speed ! " my reader will exclaim ; but 
I can assure him that this is going on continually, sometimes 
for months and years, so long as phosphorus gleams in the 
dark. Indeed we learn from optical science that even in the 
smallest particle of every material body, nay, even in what 
we deem empty space, there are colossal forces in perpetual 
action before which the ordinary energies known to us sink 
into absolute insignificance. Modern chemical research 
has made clear that the phosphorescence is due to a slow 
chemical combination. We must picture the phosphorus 
as giving off a vapour. Even as we watch it faintly gleaming 
we must imagine millions of its molecules pouring out from 
its surface into the air, and there colliding with the countless 
millions of oxygen atoms whirling and flying about in every 
direction. As the result of mutual collisions the two sets 
of atoms combine to form the white smoky luminous fumes 
which we see arising from all over the exposed surface of 
the phosphorus. The action is represented by the following 
equation : 

P 4 + 30 2 = PA 

Phosphorus Oxygea Phosphorus Oxide. 

One of the most remarkable peculiarities of phosphorus is 
its ready inflamability. A piece if left out in the air gradually 
increases in temperature as the result of slow oxidation until 
at last it melts at 44.3 C. and immediately afterwards takes 
fire spontaneously at 45 C. The slightest degree of friction, 
especially contact with the warm fingers, will also cause it 
to inflame. Phosphorus, therefore, is a very dangerous 
substance, and in practice is always kept under water. This 



3 io MODERN CHEMISTRY 

ready inflammability of phosphorus naturally suggested an 
easy and certain way of obtaining fire, but the expense of 
the substance, which at that time ranged from ten to sixteen 
ducats the ounce, entirely prevented its general use for this 
purpose. It was not until Scheele (in 1771) showed that it 
could be obtained cheaply from bones that it was possible 
for any steps to be taken in this direction, and even then 
it was not until fifty years later that it began to be manu- 
factured in quantity for the purpose in Paris. Bones, you 
must know, consist principally of a chemical combination 
of phosphorus with calcium and oxygen, called calcium 
phosphate, and having the formula Ca,(P0 4 ) 2 . 

The phosphorus is now directly boiled out of them by 
heating this material, mixed with sand and charcoal, to a 
terrific temperature in an electric furnace, when the following 
reaction takes place : 

2Ca 3 (P0 4 ) 2 + 6Si0 2 + 10C = P 4 + 10CO + 6CaSi0 3 

Calcium Sand or Carbon Phosphorus Caibon Calcium 

Phosphate Silica Monoxide Silicate. 

Naturally when once the problem of supplying cheap 
phosphorus had been solved, it was not long before attempts 
were made to use it commercially for manufacturing 
matches. About 1833 this problem was successfully solved 
by a number of persons, and the famous lucifer matches 
began to be manufactured on a large scale. These con- 
sisted of splints of wood which were first dipped into a shallow 
pan containing molten paraffin, and then into another 
containing the igniting composition. This consisted essen- 
tially of finely divided phosphorus mixed with gum or glue, 
and combined with a quantity of potassium chlorate, red 
lead, or lead nitrate, in order to increase the combustibility, 
and then some colouring matter, such as cinnabar, smalt, 
or aniline dyes in order to make it attractive to the eye. 
The matches were then placed in a drying compartment, and 
remained there until the igniting tips were dry. Then they 
were taken out, counted, and packed into boxes. All this 
was done on the largest scale, a single factory sometimes 
turning out from six to ten million matches in a single day. 



THE PHOSPHORUS GROUP OF ELEMENTS 311 

Every new substance possesses properties — sometimes of 
a most dangerous nature — which are often entirely unsus- 
pected so long as the substance is employed only in the 
laboratory, and very occasionally at best even then, but which 
become known as the result of painful experience when it 
begins to be employed on the manufacturing scale. Phos- 
phorus was no exception to the general rule. Its evil proper- 
ties revealed themselves in a truly sensational manner. 
For the employment of phosphorus in match-making had not 
been introduced for a very long time before a terrible and 
mysterious disease, quite new to medical science, made its 
appearance among the workers. It commenced with tooth- 
ache ; the teeth decayed and fell out, and then the decay 
extended to the jaw and caused excruciating pain, from 
which the sufferer was relieved only by a surgical operation 
or by death. Here is the statement of one poor woman 
who worked in a match factory for five years and then con- 
tracted the disease. " My teeth began to ache, and then my 
top jaw. I did not take much notice of it till one day at the 
factory they gave me a paper to take to the doctor. He told 
me I was to go home and stop in my room till he saw me. 
When he came he said I must have four teeth out. That 
did not do any good. Then the pain got worse. Oh ! it 
was awful. I thought I should go out of my mind with it. 
It was just as if somebody had got something scraping the 
bones in my cheek. And then he said that my husband and 
children must not be in the same room with me because the 
smell was so bad. The doctor went for his holidays, and 
while he was away lumps of my bone worked right out through 
my cheeks — it was festering dreadful. I kept the bone to 
show him. . . . " Naturally after this it will be understood 
that the suffering is terrible. Sometimes the disease eats 
away the roof of the mouth and the inside of the nose, some- 
times extending upwards so that the sight is lost, together 
with the whole of the jaw-bone. Then the liver becomes 
enlarged and full of sores, and very often the patient dies 
after dreadful sufferings. This disease, which completely 
baffled medical science, was known to the workers as " phossy 
jaw," and to medical men as " necrosis." It appears to 



3 i2 MODERN CHEMISTRY 

have been brought about by inhaling phosphorus fumes. It 
raged in many factories and caused a great public outcry. 
Good ventilation and perfect cleanliness were found to do 
much towards diminishing the outbreak, but so long as 
ordinary phosphorus was employed, even in spite of all pre- 
cautions, the disease, sooner or later, made its appearance. 

The employment of ordinary phosphorus in matches had 
other serious disadvantages. They were luminous in the 
dark, liable to ignition on a warm mantelpiece, they absorbed 
moisture, and became useless with age. Still worse, since 
ordinary phosphorus is terribly poisonous many deaths 
occurred from children accidentally getting hold of these 
brightly coloured matches and sucking them. At the same 
time match-tops were used for the purpose of murder and 
suicide — especially on the Continent. Thus Dr. Blyth, writing 
in 1884, could even then state, "Phosphorus may be con- 
sidered as the favourite poison, which the common people on 
the Continent employ for the purpose of self-destruction. It is 
an agent within the reach of any one who has two sous in his 
pocket wherewith to buy a box of matches, but to the 
educated, and to those who know the horrible and prolonged 
torture ensuing from a toxic dose of phosphorus, such a means 
of exit from life will never be favoured."* 

The first symptom of phosphorus poisoning is a terrible 
feeling of pain in the stomach. Then follows vomiting of 
garlic-smelling substances, which are luminous in the dark. 
If the patient survives this stage, jaundice makes its appear- 
ance, and the patient dies in convulsions or sinks into a coma. 
Sometimes a new and terrible train of symptoms set in, 
in which the patient dies, sometimes after six days of agony, 
with blood oozing from eyes, nose, lungs, and bladder. 

Naturally, all the Governments of the civilised world were 
soon in arms against this new scourge of civilisation. Some 
countries, such as Denmark and Switzerland, went even so far 
as to forbid the employment of ordinary phosphorus in 
match-tops at all. But a remedy was at hand. In 1845 
the famous chemist von Schrotter discovered how to convert 
the yellow or ordinary phosphorus into a non-poisonous 
* "Poisons, Their Effects and Detection," p. 199 (1884). 



THE PHOSPHORUS GROUP OF ELEMENTS 313 

variety. It appears that one day he was heating ordinary 
phosphorus in a vessel out of contact with air to a tempera- 
ture of between 240 C and 250 C, when he observed that after 
a time it solidified and changed into a hard red mass. This 
modification of phosphorus differed in an altogether extra- 
ordinary way from the ordinary yellow sort. Thus it gave 
off no fumes, had no smell, was not poisonous, and was 
not luminous in the dark. It was so hard to inflame that it 
could be heated to 260 C. before it took fire. At a 
higher temperature it was partially converted back into 
ordinary phosphorus. 

Very soon attempts were made to replace the yellow 
phosphorus in matches by this red variety, and thus avoid 
all danger of poisoning. The matches made with it appeared 
excellent. They were not luminous in the dark, did not 
take fire on a warm mantelpiece, did not contract damp, 
and would keep for any length of time. 

There was, however, a difficulty. When red phosphorus 
is brought into contact with potassium chlorate a slight touch 
is often sufficient to produce an explosion and blow the match- 
maker and his matches into the air. Many vain attempts 
were made to form a paste, and many accidents and some 
deaths occurred in consequence; but at length the happy 
idea occurred in 1855 to a Swedish manufacturer named 
Gundstrom not to attempt to make a paste at all with the 
red phosphorus, but to make the match lighter bring the 
essential ingredients together in the act of striking the match. 
Thus the famous Swedish safety match was born, which from 
Jonkoping in Sweden spread throughout all the world. 
~ In the ordinary match all the igniting composition is put 
on the splint, and the match can be ignited by friction on 
any rough surface. In the safety match, however, the 
composition is divided between the splint and the friction 
paper attached to the box. The composition put on the 
splints contains no phosphorus at all and is not poisonous. It 
consists of potassium chlorate, potassium bichromate, red 
lead, and antimony sulphide, while the friction paper is coated 
with a mixture of amorphous phosphorus and antimony 
sulphide. 



314 MODERN CHEMISTRY 

The use of ordinary yellow phosphorus for friction matches 
has been forbidden in many countries, including England, 
and matches which strike on any dry surface are now largely 
made in which the so-called phosphorus sesquisulphide, 
P 4 S 3 , or Schenk's scarlet phosphorus, replaces the ordinary 
phosphorus. Such matches are less liable to accidental 
ignition and can be manufactured without serious poisoning of 
the workmen. 

A visit to a large match-making factory is, indeed, well 
worth making. In them may be seen vast halls where are 
installed machines, miracles of mechanical ingenuity, which 
transform a log of wood into the finished match, completing 
in one operation a task that in the old days passed through 
eight or nine stages. 

We will quote from a pamphlet issued by Messrs. Bryant 
and May, one of the largest firms of match manufacturers 
in the United Kingdom. This pamphlet, called " The 
Evolution of the Match," describes one of their factories 
as follows : — 

" In one great room there are sixteen of the famous machines which 
cut the matches from blocks of wood, dip them in paraffin, tip them 
with composition, and finally pack them in boxes, entirely without 
assistance from the human hand. At the very start of operations 
a man feeds blocks of wood into the jaws of the machine, and 
thenceforth the mechanical monster does its own work. 

Seizing the block from the man's hand, the machine grips it 
between rollers and forces it against rows of keen edged cutters which 
are so arranged that there is little or no waste. Each of these cutters 
(and there are usually forty-eight in a machine) severs a piece of wood 
of exact size and shape. At the same moment a palate rises from 
beneath, which thrusts these little pieces of wood into a moving 
cast-iron band, or rather into small holes in this band, from which 
the embryo matches project like bristles. This travelling band is 
about 700 feet in length, and follows a serpentine course in its journey, 
which occupies about an hour from start to finish, the speed being 
regulated according to the temperature so that the matches may be 
quite dry when they reach the boxes. When the band arrives at 
the finishing point, a steel oar punches out the matches stuck in its 
surface and they fall into the inside boxes placed ready to catch 
them. These boxes are kept continually shaking so that no spaces 
are left and the matches fill them completely. As the inside boxes 
fill, a steel arm presses them forward into their covers, and they are 
passed along a trough in dozens, quickly wrapped in paper and sealed 






THE PHOSPHORUS GROUP OF ELEMENTS 315 

by a machine. Quick-fingered girls then wrap twelve of these dozen 
packets, and we have the gross parcels so familiar in the shops. . . . 
For those who enjoy statistics, we may pause at this part of the pro- 
ceedings to consider some figures. The forty-eight cutters cut forty- 
eight matches at each stroke, and make from 150 to 230 strokes per 
minute — say 200. Therefore each machine cuts 9,600 matches in a 
minute, or 576,000 in an hour. Taking the working day at ten 
hours, a simple calculation shows us that the sixteen machines in this 
room are on a moderate estimate capable of cutting no fewer than 
92,000,000 of matches in a day. But this is only one room in one of 
the factories. At Liverpool alone the average daily output of matches 
placed end to end would cover a distance of 7,000 miles. Add to this 
the output in London of . . . Patent safety matches, Swan Vestas, 
and all the different kinds of matches, and you arrive at figures which 
the ordinary mind quite fails to grasp." 

Indeed, we read with amazement that this one firm, in a 
single year, can produce 90,000 millions of matches, and up- 
wards of 100,000 miles of wax vestas and tapers — enough 
to girdle the earth some four times round ! Every year 
thousands upon thousands of huge pine trees, growing tall 
and straight in the virgin forests of America, are cut down 
and turned into matches. The company is one of the largest 
timber merchants in the world, and in California own 
more than 75,000 acres of pine forests. And this is one 
firm alone ! Equally vast firms exist in Sweden, Germany, 
Russia, and America. 

Although phosphorus acts as a fearful and mysterious 
poison, yet, strange to say, it is an essential constituent of the 
animal body. Is it not a curious paradox that a substance 
so fatal to human life is so necessary for its maintenance ? 
In the body of a normal adult man there is as much phos- 
phorus as occurs in 800,000 of the old phosphorus matches ; 
and since three of these matches have been known to produce 
death, the phosphorus obtainable from a single man could 
destroy or poison over a quarter of a million human beings ! 
The phosphorus is mainly concentrated in the body as calcium 
phosphate, which, as we have already stated, forms the hard 
mineral matter of which the solid bone is built up. Large 
amounts also occur in the brain and nerves, and, indeed, the 
element is always present in the nuclei of the animal cells, 
whether nervous or muscular. The phosphorus atoms seem 



316 MODERN CHEMISTRY 

in some way to play a very important part in the mysterious 
inner processes of life. They are essentially connected with 
the mechanisms for carrying the nervous impulses which are 
continually flashing through brain and nerve, and with the 
reproductive cells. 

The phosphorus reaches the animal body from plants ; and 
we find that all the essential parts of vegetables, especially the 
fruit and seeds, contain the element. To plants it passes 
from the soil, the great mother of all living things, which 
contains within it all the elements necessary for the susten- 
ance of life. Therefore, the mere fact that phosphorus is 
an essential constituent of all the vital parts of living matter, 
whether of animal or vegetable origin, must at once teach 
us that phosphorus occurs in the soil ; and this is so. The 
presence of phosphorus in the ground is an essential condi- 
tion for the fruitfulness of the land. In soil devoid of phos- 
phorus no plant can grow. Deprive rich meadow land of its 
combined phosphorus and it grows barren and refuses to 
yield as before unless the loss is replaced by manure. If 
phosphorus occurs in the soil, it must also occur in the running 
waters which pour from the land; and since these waters 
run into the sea, the oceans also must contain it, and it goes 
to nourish sea-plants. The fishes which dwell within the sea 
absorb it from the sea plants around them. 

Since the great German chemist, Liebig, during the last 
century showed the importance of phosphorus for vege- 
tation, manures rich in this element have been employed 
on a large and rapidly increasing scale in agriculture ; and 
thus it will not surprise the reader to hear that ground bone 
dust, which consists principally of calcium phosphate, is a 
valuable manure, and that very large quantities of bone 
from the flesh extract ranches in South America are now used 
for this purpose, though the supply from this source is far 
too small to satisfy the demand. So it comes about that 
other phosphorus rich materials are eagerly sought and used. 
For many years guano was employed for the purpose. Off 
the coast of Peru there occur some rainless and barren islands 
on which millions of sea birds have dwelt for unknown 
thousands of years, undisturbed by man or beast, taking their 





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TOE PHOSPHORUS GROUP OF ELEMENTS 317 

nourishment from the fish of the tropical seas around. In the 
course of ages they heaped up vast deposits of their droppings, 
sometimes 180 feet thick. These deposits contained no less 
than thirty-one per cent, of calcium phosphate, besides 
valuable amounts of nitrogen and other elements necessary 
for plant life. For a time these great guano deposits were 
mined on a great scale, and imported to Europe for the use of 
agriculturists ; but within recent years the supplies have 
been almost completely exhausted, and so men were com- 
pelled to look about for other sources, and in our own days 
natural deposits of phosphate have been worked. Thus 
a large amount of the phosphorus manufactured in England 
is prepared from sombrerite, an impure calcium phosphate 
found in the desert island of Sombrero in the West Indies. 
Again, in the Spanish province of Estremadura there occur 
enormous masses of almost pure phosphate, termed " phos- 
phorite/' and from this most valuable manures are manu- 
factured.' In order to render such phosphates soluble and 
consequently more readily assimilable by plants, they are 
treated with sufficient sulphuric acid to convert them into 
the soluble monocalcium phosphate, thus : 

Ca 3 (P0 4 ) 2 + 2H 2 S0 4 = 2CaS0 4 + CaH 4 (P0 4 ) 2 

Tricalcium Sulphuric Calcium Monocalcium 

Phosphate Acid Sulphate Phosphate. 

Another important source of phosphorus is apatite, 
3Ca 3 (P0 4 ) 2 +CaCl 2 , which often contains 5-7 per cent, of 
the element fluorine, and the phosphorus rich slags formed in 
steel making. 

It had long been remarked that parts of England which 
were covered by beds of the geological formation known as 
" Lower Greensand " made admirable wheat-land. It had 
also been noticed that the finest hop-lands — those of Farnham 
and Tunbridge, for example — lay upon them, but that the 
fertile land was very narrow, and that vast sheets of the 
Lower Greensand were scarcely worth cultivation. What 
caused this wonderful difference in tracts of, apparently, 
the same sort of soil ? The clue was furnished by a farmer 
who brought to Dr. Henslow some fossils which he had found 



318 MODERN CHEMISTRY 

in these fertile tracts of land. He examined them, and 
found at once that they were not, as fossils usually are, 
calcium carbonate, but calcium phosphate. " He said at 
once, as by an inspiration, you have found a treasure — not 
a gold-mine, indeed, but a food-mine. Only find enough of 
them, and you will increase immensely the food-supply of 
England, and perhaps make her independent of foreign phos- 
phates in case of war." His advice was acted on, and now 
those beds of phosphates are mined, and used extensively 
for manures. They are the so-called " Coprolite Beds," 
and are found everywhere in the Greensand underlying the 
chalk. Geologists tell us that they are the fossil excrements 
of fishes and saurians that lived, I do not know how many 
millions of years ago, in the Lias seas. The name is from the 
Greek, " kopros," dung, and " lithos," a stone. " How to 
explain the presence of this vast mass of animal matter in 
one or two thin bands right across England I know not. 
That the fossils have been rolled on a sea-beach is plain 
to those who look at them, but what caused so vast a destruc- 
tion of animal life along that beach must remain one of the 
buried secrets of the past." * 

So that, dear reader, you may have in you now atoms 
of phosphorus derived from wheat, which in turn obtained 
them from the coprolite manure with which it was nurtured, 
— atoms that, — just think of the wonder of it ! — once formed 
part of fierce terrible fish and reptiles which swam in the 
warm seas millions and millions of years ago, and tore 
and fought and died along a sun-lit beach, long ages 
before man or beast, or even present-day England, existed 
at aU ! 

Phosphorus occurs also scattered through those grand old 
volcanic rocks which form the greater part of the vast skele- 
ton of the world's crust. In our chapter on silicon we gave 
a table of Clark's analyses of these rocks, and from this you 
will see that in them phosphorus, reckoned as phosphorus 
pentoxide (P 2 5 ), occurs to the extent of 0.22 per cent. This 
is what makes volcanic soils so very fertile ; for volcanoes 
pour these rocks out in a fiery stream over the land, and 
" Half Hours Underground," p. 262. 






THE PHOSPHORUS GROUP OF ELEMENTS 319 

blast them up as ashes high into the air, which on falling some- 
times cover hundreds upon hundreds of miles of land to the 
depth of several inches, and act as a manure, rendering the 
ground wonderfully fertile. Of course, when the solid lava 
first cools on the ground, it forms a hard barren mass ; 
but soon the rain sets to work upon it, and with that, as by 
a spade, century after century, age after age, the lava stream 
is dug down and dispersed, atom by atom, all over the fields 
as rich manure. Therefore from the volcanic rocks (and if we 
dig deep enough we shall always come upon them) the phos- 
phorus gets into the sedimentary rocks, and from these into 
the mud and broken soil which covers the hard rock, and 
into the plants which grow in it, and finally into the bodies of 
the animals which devour them. Thus Nature " can put 
into your veins things which were spouted up red hot by 
volcanoes ages and ages ago ! " 

And now, dear reader, I am going to let one single atom of 
phosphorus — and there are innumerable millions of them in 
every piece of bone you see, and in every box of matches — tell 
you its story. This phosphorus atom is, to be sure, a very tiny 
thing, so small that no human eye has ever seen it, so minute 
that a hundred million placed in a row would not cover the 
breadth of your little finger nail ; and yet what a wonderful 
story this tiny scrap of phosphorus can tell of its long journey 
down the ages ! Yes, a story wonderful beyond all measure, 
more wildly grand, more terrible, and more romantic than 
any story ever told by man. Much of its tale would be 
incomprehensible because it would deal with mysteries of 
creation beyond our ken of mind, but some parts of it 
would be clear to us. I can imagine it beginning its tale 
thus : — 

" Where was I born ? Ah, that I cannot tell you. It was 
far, far away from here, deep in the endless abyss of space, at 
an epoch so distant that even the earth on which you live 
had not been formed as yet ; not even the great sun, now 
blazing in his glory, nor any of the innumerable multitudes 
of stars of the great universe now shining in the sky, had as 
yet come into being. No, they were mere cold whiffs of 
invisible vapour, scattered over all space, remnants of 



320 MODERN CHEMISTRY 

worlds vanished aeons before this great universe began. 
Out of the vast I came, born into that great sea of 
Ether which stretches unbroken from star to star 
through all the endless depths of space. Some vast 
change, some murmuring and stirring of gigantic forces in 
its bosom, forces scarce known, scarce dreamt of, but work- 
ing there in irresistible might, first brought me into being, 
and I hung suspended in the great void. It was utterly 
cold and utterly dark, and gleaming afar in the distance 
I could see the myriad fires of the great worlds and suns of 
space shining at me through the darkness. How long I 
hung in the void I know not. It was millions upon millions 
of years. Then atoms began to gather round me, stream- 
wise, coming from afar in phosphorescing torrents, and I 
perceived that I already formed part of a mighty mass of 
gas, a huge nebula, which stretched its gigantic arms out 
for millions of miles, like vast flaming swords, through the 
darkness of space. And so I hung for aeons of ages, while 
atom after atom in an endless stream flashed past me in the 
gloom, while the great nebula slowly drew together in its 
glory, and began to take shape and form. Then the tem- 
perature began to rise in leaps and bounds, it grew stifling 
hot, and great lightnings flashed and quivered about me, and 
we atoms crowded more and more together, colliding, whirl- 
ing, flying. Each second I < mote a thousand million atoms 
and at each collision my motion grew more and more violent, 
until after millions upon millions of years of this tumult, 
I found myself part of an immensely hot flaming mass of gas, 
part of an embyro sun. There in the whirl and roar of this 
elemental flame I remained for unthinkable ages, but at last 
vast thunders beneath and around me made me aware that 
something tremendous was happening. It was a world — 
my first world — gradually condensing out of the fire mist, and 
the gigantic explosions which occurred from tim Ho time 
were just great seas of boiling rock leaping upwards. But I 
will spare you the account of how I entered into that world, 
and saw it slowly form and develop into a fair planet, 
covered with wonderful swarming masses of living creatures, 
with great cities filled with busy life, and wonderful civilisa- 



THE PHOSPHORUS GROUP OF ELEMENTS 321 

tions. Nor will I tell of how that world grew old, and 
passed into a vast desert, and finally, after wandering for 
aeons of ages in darkness and silence, burst suddenly forth 
into flame, the victim of a great cosmical catastrophe, 
and, like a bubble, vanished, exploding into incandescent 
gas. Nor will I tell you of how, far flung, I fell upon another 
world, and saw this world too in time perish ; and of how I 
passed from world to world, and formed part of world after 
world, wandering in mighty migrations through space, until 
at last I joined the fire mist from out of which, ultimately, 
this present world of yours condensed amidst titanic convul- 
sions. You will, therefore, see that even before your world 
began, I was-old, immensely old. I will pass over all this 
and come to a time quite recent, merely a few hundred 
million years ago, when I found myself forming part of the 
molten fire underground. Here I lay for age after age, while 
the land above me was being eaten away by wind and rain 
and storm, and was hurried — continent after continent 
crumbling into ruin — into the great ocean waiting patiently 
to receive it. Now I was urged upwards by vast forces, 
slowly, steadily, for thousands of years, until finally I was 
uplifted to form part of a hard, cold rock, which soon reared 
itself into a mighty cliff, beaten upon by wind and rain and 
storm ; I have a dim recollection of looking out from the cliff 
face upon a wide-spread blue sea, filled with strange vast 
monsters, which have long since vanished from the earth. 
But at last the cliff was washed away and I passed into the 
great body of the sea, and was absorbed into a tiny plant, 
living beneath the salt waters ; but this was devoured by a 
glittering gorgeous fish, and so I entered his body. Then this 
fish was devoured by a reptile, which, creeping out of the 
water, entered a swamp and died, and its huge body decaying, 
I was washed into the soil, and there meeting with the 
rootlet of a plant, I entered into and formed part of it; 
and this was eaten by an animal ; and so I entered into 
its body and formed part of his bones. While we were 
crossing a ravine one bright sunshiny day, millions of years 
acp, a green monster flashed out upon us and slew my 
master and devoured me. After a time my new host was 
x 



322 MODERN CHEMISTRY 

also slain in a similar manner, and his body decaying in the 
rank grass and vegetation of the swamp, I was ultimately 
washed out to sea in a sudden flood, which, coming down 
from the hills, swept me away. Here I mingled with the 
mud at the bottom of the sea, and stayed there for millions 
of years, and became covered over with mighty layers of mud 
and sand, and sank ever deeper and deeper into the earth, 
and at last once more felt the glow of the nether fires. Here 
in the great gleaming furnaces of the deep I remained for 
many a million of years, while miles above me the world 
changed and developed, mountains came and went, new and 
strange creatures evolved, developed, filled all the earth, 
and died out again. One day I was hurled forth amidst 
vast thunderings through the throat of a great volcano, and 
formed part of a molten lava stream, which in time became 
a fertile field covered with waving crops and golden grain. 
Then I entered into a grain of corn, and was devoured by 
a man living thousands of years ago, a mere savage you would 
term him, wild and fierce. From him I passed to earth 
once more, and since then have been passing in a ceaseless 
round of change through the bodies of living creatures. I 
have flown through the air in a bird, I have swum in the 
sea in a fish, I have roamed over the earth in a beast, I have 
formed part of innumerable plants. But the full tale would 
only weary you, wonderful as it is. One day, a few years ago, 
I was devoured by an ox while forming part of a piece of 
grass, and soon by the mysterious chemical forces of its 
body I was made to form part of its bone. The great beast 
was slaughtered by men, and his flesh eaten, and his bones 
burnt to a fine white dust in a furnace. Out of this dust I, 
the tiny phosphorous atom, was distilled in a furnace and 
found my way to a match factory, and am now in this little 
match-box lying on the table before you. Is my journey 
finished ? Oh dear no, far from it. I shall go on changing 
and journeying and dancing, age after age, even until the 
world fades away like a mist, and long after all that you see 
and hear around you has crumbled away and vanished into 
the awful maw of time. I have been taking part in the great 
dance of atoms which forms the basis of all passing things 






THE PHOSPHORUS GROUP OF ELEMENTS 323 

and events, for millions upon millions of years, and shall 
continue to do so for millions and millions of years to come. 
I may, indeed, see this world perish, and may yet dance in 
worlds as yet unborn. My future will be probably even more 
strange than my past." 



CHAPTER XV 

FIRE, FLAME, AND SPECTRAL ANALYSIS 

A poker placed in a fire becomes hot, and after a time begins 
to emit a dull red light. As the temperature increases the 
light changes to yellow, and at the highest temperatures a 
dazzling white light is emitted. Heat, then, accompanies 
and produces light.* Heat is supposed to be a swift bodily 
motion of the molecules. When we heat a body we are merely 
increasing the motion of its molecules, and this increased 
motion becomes visible to us as light. How ? Let me 
explain. Go out on a dark clear starry night and look up into 
the heavens above. Realise that you are looking into infinite 
space, extending upwards for ever and ever without end or 
beginning, in which the world flies as a dimensionless point. 
This vast void is not really empty. Physicists tell us it is 
filled with that wonderful elastic medium called the Ether, 
which is 2,000 million times denser than lead, and yet allows 
matter to pass freely through it without noticeable friction 
or viscosity. It is this medium which bears the light of the 
stars to us. The molecules are particles of matter plunged 
in it, accepting its motions and imparting theirs to it. When 
we heat a body we increase the motion of its molecules, and 
these, beating upon the ether, set up little tremors or waves 
in it in much the same way that the sudden impact of a 
stone with water sets up water waves. These quiverings of 
the ether fly through space with the velocity of 186,000 miles a 
second, and bursting upon the eye produce the sensation of 
light ; but light is produced, not so much by the coarse bodily 
movements of the molecules as a whole, as by the very fine, 
enormously rapid motions going on within them. Each 

* Not always. Phosphorescing bodies often emit much light but 
yet remain cold. 

3 2 4 







FIRE, FLAME, AND SPECTRAL ANALYSIS 325 

molecule, in fact, is composed of still tinier particles revolving 
in little orbits like planets round the sun. Still, the coarse 
bodily movements of the molecules, by causing molecular 
collisions, generate these finer move- 
ments in their internal parts, and thus 
it comes about that light usually 
accompanies heat. Hence, whenever 
we can by any means increase the 
motion of the molecules sufficiently, we 
shall usually succeed in obtaining light 
Fig. 6 9 -SyphoXg un- as a secondary effect One way of 
burnt Gas from the increasing the motion of the molecules 
interior of a Candle i s to let them act chemically on each 
other. This is very easy to do, because 
we know that different sorts of atoms often attract each other 
with a mighty power. If, therefore, we bring different sorts of 
molecules close together, their atoms will rush together and 
combine to form new bodies. The act of rushing together and 
colliding produces violent motions within the tiny molecular 
worlds, and thus causes heat motion together with its attend- 
ant light motion. Fire is due to the intense motion of the 
atoms caused by the act of chemical union. For example, 
when coal burns in air or oxygen the carbon atoms are 
combining with the oxygen atoms, thus : — 

C + 2 = C0 2 

Carbon Oxygen Carbon Dioxide. 

Magnify the whole process a hundred million times and we 
should see the burning coal as a vast surface composed of 
myriads of moving and rotating atoms of carbon ; while 
showering down upon them from all sides in a never-ending 
stream we should see the oxygen atoms rushing, driven 
towards the carbon atoms by intense attractional forces. 
Every oxygen atom as it reaches the carbon surface has 
its motion of translation destroyed by collision, and the most 
intense, enormously rapid, internal motions set up among the 
still smaller particles which build them up. These internal 
motions shine forth as light, while the coarse bodily move- 
ments of the molecules produce the sensation of heat. 



326 



MODERN CHEMISTRY 



In all sorts of combustion the case is similar. Thus the 
heat and light of our gas or candle flames are due to the 
clashing together of the oxygen of the air and the constituent 
molecules of our gas and candles. It is the impact of the 
oxygen atoms against the atoms of sulphur and phosphorus 
which produces the heat and flame observed when sulphur 
or phosphorus burn in air. It is the collisions of chlorine 
and antimony atoms which produce the light and heat 
observed when powdered antimony is thrown into chlorine 
gas. It is the clashing together of sulphur and copper atoms 
which causes the incandescence of the mass when these bodies 
are heated together. In short, all cases of combustion are 
due to the collision of atoms which have been urged together 
by their mutual attractions. 

The reader must not imagine that this is a full explanation 
of the phenomenon of flame. Far from it. The most 
common things about 
us are often the most 
wonderful, and it ex- 
cites no surprise to 
discover that when we 
study closely such an 
ordinary thing as a 
burning gas jet, we 
find that it has a con- 
stitution wonderful 
beyond all conception. 
The chemical changes 
which occur within it 
are of such a complex 
nature and succeed 
each other so rapidly 
that chemists are even 
now uncertain as to 
exactly what is going 
on inside it. This 
much, • however, is 

^<sr~4-^;-n • w;+v,i« +1-,^ Fig. 7°- — Match in a Gas Flame.- Inside is a 

certain . Within the c J x core of whmnt gas> into which a 
flame we have a core match may be thrust without inflaming. 




FIRE, FLAME, AND SPECTRAL ANALYSIS 327 

of gas as yet unburnt, and outside the flame we have the 
oxygen of the air. The external surface of the core of the 
gas is in contact with the air, and here it is that the atoms 
clash together (and sometimes fly to pieces in so doing, shoot- 
ing out a stream of electrons) and produce heat and light by 
their collision. 

The presence of the unburnt core of gas may be shown in 
many ways. For example, a bent glass tube may be brought 
into the centre of the flame, when the unburnt gases will pass 
up the tube and may be lighted at the other end. Or the 
head of a match may be thrust quickly into the centre of the 
flame and held there for some time without the phosphorus 
catching fire, while the wood is charred and may even take 
fire where it is in contact with the hot external layer of gas. 

Outside the internal core of unburnt gas occurs an intensely 
luminous layer of burning gas, and outside this again an 
almost non-luminous but intensely hot layer of burning gas. 
In this last layer the oxygen of the air unites with the 
hydrocarbon, burning it completely to carbon dioxide and 
water, thus : — 

+ 2H 2 

Water. 



CH 4 


+ 


20 2 = 


co s 


Methane in 




Oxygen 


Carbon Dioxide 


Coal Gas 




in Air 





Here the flame is hottest but non-luminous. 

Just inside this we reach the luminous layer of gas. Here 
the oxygen is scanty, and the heat from the outer layers 
acting on the still unburnt gas within has decomposed it 
into innumerable solid particles of carbon or soot, which, 
scattered in the midst of a burning gas, are raised to a state 
of intense incandescence, and radiate out light copiously. 
Indeed, it is to these tiny particles of solid white-hot carbon 
that the light of our gas jets is mainly due. Very dense 
vapours, however, when burning, give out much light, 
although no carbon separates out, and some writers have 
considered that the luminosity of flame is due, not to the 
production of carbon particles at all, but to the formation 
of dense gaseous hydrocarbons, or to the generation of acety- 
lene, all of which burn with an intensely luminous flame. 



328 



MODERN CHEMISTRY 



This may, indeed, be 
the case in some 
measure, but there can 
be little doubt that in 
a luminous flame there 
really do exist innumer- 
able multitudes of par 
tides of carbon which 
greatly contribute to 
the luminosity. This 
is proved by the fact 
that when an image of 
a flame standing in the 
track of a beam from 
an electric arc is cast 
upon a screen, the 
image is seen to be 
partially opaque in the 
part of the flame which 
is most luminous. Also 
when a beam of sun- 
light is thrown by 
means of a lens across 
a flame, two patches of 
light are seen on either 
side of the cone formed 
by the flame, such as 
would be produced by 
letting the solar ray fall 
upon a cloud of dust or 
smoke. Moreover, these 
patches of light exhibit 
all the polarisation 
effects of light scattered 
by a cloud of small 
particles. 

The combustion of 
a candle or an oil lamp 
that of a jet of gas 



i 




Norv luminous 



5umirvg ga^ 

[filled with in- 

^numerable ^ 

•jele* ofwHite 

hot carbon. 

t 

Un burnt gas 



from wick. 



Fig. 71. — Section of a Candle Flame. On 
the inside occurs a layer of unburnt cool 
gas. Then comes a luminous layer of 
burning gas, and outside of all is a non- 
luminous layer of burning gas. The 
flame, small as it is, is a vast universe of 
colliding atoms. In the billionth part 
of a second there occur no less than 
2,800,000,000,000,000,000 atomic col- 
lisions, each attended with its own 
definite incidents, and regulated by laws 
with a precision as great as that which 
guides the collision of suns in space, or 
swings the planets round their orbits ! — 
so wonderfully complex is this common 
object! 

is in principle the same 
A candle is a rod of wax 



FIRE, FLAME, AND SPECTRAL ANALYSIS 320 



tallow, through which passes a cotton wick. When the 
wick burns it melts the wax at its base, and the liquid thus 
produced ascends the wick by capillary attraction and at the 
summit is converted by the heat into vapour. This vapour 
is a hydrocarbon like coal gas and burns like it. 

We have just seen that to the existence of solid carbon 
particles the light of our lamps is mainly due ; but the 

existence of these 
particles, in the free 
state, implies the ab- 
sence of oxygen to seize 
hold of them. If at 
the moment of their 
liberation from the 
hydrogen with which 
they are at first com- 
bined, oxygen atoms 
were present to com- 
bine with them, the 
carbon particles would 
never separate out at 
all, and so we should 
no longer have their 
light. Consequently 
when we mix a suffi- 
cient quantity of air 
or oxygen with the gas 
issuing from a jet, so 
that the oxygen pene- 
trates to its very heart, 
we find that the light 
disappears. 

Bunsen's burner was 
invented for the ex- 
press purpose of 
destroying by quick 
combustion the solid 
carbon particles. The 
gas, rushing out of a 





Hi 






\l 






e 


1 




e 




^^— , 




-% d 




j*® L 'Wr~ — a 


=S3 


^L ^F ^^\ 


^— ~28«Bli 



Fig. 72 . — A Bunsen Burner, as used in the 
Laboratory. The gas streaming up 
through the jet a sucks in with it 
through the air-holes c and d a supply 
of air, which, by supplying oxygen to 
burn up all the carbon before it is set 
free, produces an intensely hot, non- 
luminous flame at the summits 



330 MODERN CHEMISTRY 

central jet, passes unburnt up the tube (ee) and aspirates 
air with it through the holes (cd). The mixture of 
gas and air burns at the top with a pale bluish, smoke- 
less flame. Heat is the thing here aimed at, and 
the almost non-luminous flame is much hotter than an 
ordinary flame, because the combustion is much quicker, 
and therefore more intense. If we stop up the holes at the 
base, the supply of air is at once cut off, and the flame at once 
becomes quite luminous. We have now a core of unburnt 
gas surrounded by a burning gaseous shell. 

On admitting air once more the flame again becomes 
non-luminous. This burner is now universally used, not 
only in chemical laboratories, but in almost every household 
where a supply of gas is laid on. By its aid we obtain 
an intensely hot, clean flame, by means of which the chemist 
as well as the housewife can carry out their manifold 
duties. The invention of this burner, together with the 
invention of the gas mantle, undoubtedly saved the gas 
industry, which was threatened with complete ruin by the 
rise of electric lighting. 

Nearly twenty years ago Dr. Carl von Welsbach was investi- 
gating some elements of the rare earths. He found that their 
oxides when heated gave out an intensely brilliant light 
which far exceeded that of lime-light, and it soon occurred 
to him that this incandescence could be increased by soaking 
a piece of cotton with a solution of these substances and then 
burning it. This was the germ of a discovery which not 
only saved one enormous industry from threatened ruin, but 
actually created another ; for he found that the organic 
matter of the cotton burnt away and left a perfect image of 
its fabric, composed out of the oxides of the elements taken, 
which glowed in the Bunsen flame with a wonderful brilliancy 
and beauty. In an instant the idea of the now familiar 
gas mantle had occurred to him, and, being a man of action, 
in a short time he was actually manufacturing them in 
thousands. 

Of all the rare elements, the oxide of the element thorium, 
called Thoria, Th0 2 , yields most light ; but strange to say, 
pure thoria alone gives but a feeble light. It must be mixed 






FIRE, FLAME, AND SPECTRAL ANALYSIS 331 

with one per cent, of another rare oxide called ceria in order 
to bring its light-giving power to a maximum. The modern 
gas mantle is, therefore, composed of ninety-nine per cent, 
of thoria and one per cent, of ceria. Thousands of attempts 
since made to improve upon this composition have failed. 

If you were to ask me how we are to explain the wonderful 
power of light emission awakened in the thoria by this trace 
of ceria, I am sure that I could not tell you. We are here 
standing on the borderland of a strange region of facts — the 
influence of impurity on bodies — whose exploration has, 
indeed, hardly yet begun ; but still the fact is there and 
remains to this day unexplained. 

A short account will now be given of how the modern 
gas mantles are constructed. The first mantles were made 
of cotton, but it was soon found that they quickly lost their 
light-giving power and fell to pieces. So cotton was dis- 
placed by various siliceous grasses, especially Ramie, 
or China-grass, which is now grown in very large quantities 
in India and Southern Italy for the purpose. The grass is 
first woven into " Stockings/' which are then dipped 
into a solution of thorium and cerium nitrate. Then 
the stocking is carefully dried and burnt by being 
placed in the intensely hot flame of a pressure gas burner. 
The cloth disappears in a whiff of flame, and there is left 
behind the delicate fabric of the gas mantle. The nitrates 
under the action of heat become incandescent oxides, and 
being non-volatile preserve exactly the delicate filament of 
the original pattern. The mantle is then finished by dipping 
it into a mixture of shellac, alcohol, ether, and camphor, and 
allowing it to dry. This strengthens the mantle and allows 
it to be handled without fear of its falling into a powder,[as 
well as giving it an inflammable coating. 

Thus it was that the chance thought of a scientist, that of 
1 dipping a piece of cotton into a rare earth solution, has within 
the last twenty years created a vast industry in which millions 
of money are invested and thousands of men are employed. 
J In Germany alone over 150 million gas mantles are manu- 
factured every year, using up 330,000 pounds of thorium 
nitrate. Corresponding quantities are manufactured in 



332 MODERN CHEMISTRY 

America, England, France, and Russia, and in consequence 
a rare mineral, thoria, previously a mere scientific curiosity 
in our museums, has become of immense industrial value, 
and is now eagerly sought for all over the world. 

What is the moral of all this ? It may be summed up in 
one word : Research. It was by chemical research that the 
discovery was made, research conducted for its own sake 
in a region of chemistry which no man at that time dreamt 
could produce anything of practical value. So it is in all 
branches of research. It is no accident that those nations 
which lead in scientific research soon lead in everything else, 
be it wealth, trade, war, or peace. It is, therefore, much to be 
regretted that in England chemical research is greatly dis- 
couraged by a miserable system of public examinations which 
divert the energy of our rising youth, not into discovering new 
facts, but into absorbing by bookwork facts already dis- 
covered by others. When, jaded by innumerable and con- 
stant examinations, the student after three years' hard work 
finally passes what is known as the B.Sc. examination, 
he at once passes into the world to earn his own living, with- 
out attempting research in any of its branches, because 
research does not help him either to obtain his degree or 
a suitable post afterwards. He is only a half-finished pro- 
duct. He has merely learnt to mix his colours, but has not 
yet learnt how to use them for painting a picture, as Mr. 
Challenger once put it to me. How different a system is 
employed for training the youth in Germany and America ! 
In these countries chemical research pays the student in 
that it helps him to attain his diploma and obtain a post 
afterwards in which he can earn his living. He can do 
research, while actually studying for his degree — a thing 
quite impossible to do in England because of the incessant 
examinations, intermediate and other, which are always 
looming on his mental horizon. The German student has 
to pass an examination at the end of his school course and 
another after three years or so when finishing his university 
course, but he is not troubled by intermediate examinations, 
and usually spends his time in mental peace, doing research 
work under a distinguished professor as well as studying and 






FIRE, FLAME, AND SPECTRAL ANALYSIS 333 

attending courses of lectures to qualify for his final examina- 
tion. The final result of this system is seen in the magnificent 
and flourishing chemical industry of that great country. 

Let us now pass from this subject so painful to English- 
men, and contemplate for a short time the wonders going 
on before our eyes and all unheeded by us in an ordinary 
candle flame. Let us fasten our attention on but one 
aspect of it, upon the rapidity of the actions going on 
within it. Then, indeed, we shall excite the amazement 
of even the most unimaginative among us. In an ordinary 
candle flame there must be at the very least some 200 
trillion molecules at any single instant. In the course 
of one short second each one of these molecules on an 
average makes at least 14,000 million collisions with other 
molecules. In other words, in a single second there occur in 
a small flame nearly three billion of trillions of collisions 
(more exactly 2.8 xio 30 , or 2.8 followed by thirty cyphers) ! 
That is to say, in such an inconceivably short interval of 
time as the millionth part of the millionth part of a second 
there occur no less than 2,800,000,000,000,000,000 collisions 
between the little atomic worlds which make up a flame ! 

It must be borne in mind, too, that these encounters are 
not mere repetitions of each other, but that each has its own 
definite incidents, and is regulated by laws with a precision 
as great as that which guides the collision of mighty suns in 
space, or swings the planets in their orbits. The atoms do 
not only collide but we now know that sometimes they 
actually smash and fly to pieces as the result of the collision, 
scattering as a confused debris the electrical particles which 
build them up. We know this because free electric particles 
are being continually shot out of a flame, and give it a power 
of discharging charged bodies in the neighbourhood, some- 
what in the same way as radium, though of course not so 
intensely. Further proof of this is afforded by the fact that 
a flame is full of electrified particles, and can be resolved 
into positive and negatively charged portions by placing it 
in a suitable field. 

The smallest candle flame is thus a vast universe of war- 
ring atoms. If all this takes place in such a tiny object in 



334 MODERN CHEMISTRY 

each second, we may well ask What must be going on in an 
ordinary coal fire, or in a great smelting furnace, or in those 
vast hydrogen flames on the sun, flaring upwards for fifty 
thousand miles and more ? The mind reels in contemplating 
such numbers. The rush of events is so inconceivably vast 
as to escape our comprehension altogether. We have only 
to consider what is going on in a single candle flame in 
the billionth part of a second in order to obtain a dim 
glimpse of the inconceivable complexity and grandeur of 
Nature. 

It seems incredible that man, an animalcule crawling 
upon a grain of dust flung at random into a fathomless abyss, 
should have succeeded in actually analysing mighty suns 
millions, nay billions of miles away with as much ease as 
he analyses a piece of rock, or a lump of salt, found to hand 
on the surface of the earth ; yet incredible as it seems, man 
has achieved this, and that by quite simple methods, too. 
Can the reader guess how ? Well, merely by examining the 
fight these distant suns give forth. Each different element 
emits a different light, and we have only to split up the light 
from a distant sun into its components, in order to make 
certain of the presence of these elements in it. 

A simple illustration will show the reader how this is 
possible. Let him imagine that some enormous giant lies 
hidden in the depths of space, and is intently watching our 
solar planetary system whirling round. As each planet 
surges backwards and forwards on its mighty path round the 
sun, it doubtless sets up a periodic disturbance of the ether 
somewhat similar to those set up in our air by a tuning fork 
surging backwards or forwards (disturbances which constitute 
sound waves). Suppose the giant could only detect the pre- 
sence of the solar system by means of these immense ethereal 
vibrations. How would it appear to him ? He would 
undoubtedly sort out the disturbances in the ether into nine 
distinct sets, each set corresponding to a planet. Thus, one 
set of disturbances would have a vibration frequency of one 
year, this being the time it takes the earth to surge completely 
round the sun and return to its original position. Mercury 
would, for a similar reason, give rise to a vibration frequency 



FIRE, FLAME, AND SPECTRAL ANALYSIS 335 

of three months, Venus to one of seven months, Mars two 
years, Jupiter twelve years, Saturn thirty years, Uranus 
ninety years, and Neptune 180 years — these being the times 
that the various planets take to complete their orbits 
around the sun. 

Human beings are in very much the same position as 
regards the molecules of matter as this imaginary giant is in 
as regards the solar system. For, like the giant, a man 
cannot directly see the molecules. All that he can perceive 
are the vibrations they give forth. Each atom consists of 
a tiny planetary system, composed of a number of smaller 
electrified particles flashing round tiny orbits with the 
greatest regularity, much as the planets whirl round the sun. 
Each little particle as it goes through its tiny evolutions sets 
up a periodic motion in the ether which we call light. Here 
your conception must be perfectly clear. It is just as easy 
to picture an electron describing a little orbit in the atom as 
it is to picture the earth describing an orbit round the sun 
in the planetary system. The difference is mainly one of 
scale. The earth completes its periodic motion round the 
sun in the course of one year, while an electron completes its 
periodic motion in the atom some 400 billion times in one 
second. In fact, in order to produce visible light at all, the 
tiny electrons must flash round their orbits in the atom 
between 392 and 757 billion times a second. The slower 
vibrations produce red light and the faster violet or blue light, 
while intermediate rates of vibration produce intermediately 
coloured lights such as yellow and green. Vibrations out- 
side these limits also exist, the longer appearing as those 
electrical waves used in producing wireless telegraphy, while 
the shorter produce chemical effects, and some people have 
thought Rontgen rays are composed of excessively tiny 
waves of this nature. But the important thing to remember 
is that each particular sort of atom vibrates at its own particu- 
lar rates, which are different from the rates of vibration produced 
by any other sort of atom. Thus the vibrations emitted by 
hydrogen gas are quite different from those emitted by oxy- 
gen, nitrogen, sodium, or, in fact, by any other element. 
It is by this means, by identifying the light vibrations they 



336 



MODERN CHEMISTRY 



give forth, that chemists are able to identify elements when 
in regions quite inaccessible to man. 

The first thing to do before going further is to explain how 
these different vibration rates may be rendered visible. This 
is done very simply. The light to be examined is passed 
through a glass prism — a block of glass of triangular section 
— and the light waves are bent from their original paths. 
The most rapid vibrations are bent most, and the slowest 
vibrations are bent least. And so the different vibrations 
are sorted out on a screen as fine bands or lines of differently 




Fig, 73. — Spectroscope, 



coloured light. Fig. 76 shows several of these " spectra," as 
the resulting images are called. Each particular band repre- 
sents the vibrations of one particular electron in the atom. 
When we recognise the thousands upon thousands of lines 
which occur in the spectra of a single element, say that of 
iron, we recognise how complex a thing an atom must be. 
If, as we believe to be the case, an iron atom consists entirely 
of electrons, it must be built up of about 56,000 separate 
particles, and so there is plenty of room for complexity of 
vibration ! An atom of mercury, for a similar reason, must 
consist of some 200,000 separate moving parts. 

The instrument by which the light is examined is called 
a " spectroscope." Our illustration shows one sort (Fig. 73), 



FIRE, FLAME, AND SPECTRAL ANALYSIS 337 

but for details the reader must consult some good works 
on Physics. 

The more readily an atom agitates the ether when it 
vibrates, the more readily it accepts motion from the ether 
when the latter in its turn vibrates. Now it is well known 
that a series of slight taps may cause a considerable oscilla- 
tion in a swinging body, provided only that the blows be 
timed to the period of swing of the body. For example, 
soldiers are not allowed to march in step over suspension 
bridges, for the simultaneous tramp, tramp, tramp, of 
many hundreds of feet imparts blows to the swinging bridge 
which, if they happen to coincide with its natural period of 
swing, will gradually set up such tremendous oscillations as to 
endanger the whole structure. Indeed, a great bridge once did 
break down owing to this cause, and precipitated a struggling 
mass of soldiers, horses, and masonry into the river below. 

Now we have seen that each tiny molecule has its own 
special natural rates of vibration. If, therefore, we impinge 
on a number of similar molecules a beam of light whose vibra- 
tion frequency happens to coincide with the vibration 
frequency of one of the natural periods of swing of the mole- 
cules, the ether vibrations are at once taken up or absorbed 
by the molecules, and they start swinging themselves. So 
that the ether vibrations, after passing through a layer of 
such molecules, are almost all absorbed, and the part of the 
ray coming through (if it gets through at all) is very much 
diminished in intensity. 

If, however, the natural period of swing of the molecules 
does not happen to agree with the period of the ether vibra- 
tions, the latter passes right on, unabsorbed and undimin- 
ished by the molecules it meets with. 

Now the light given off by an incandescent gas is generally 
composed of waves of a few definite frequencies and no 
others, corresponding to the definite rates of vibration of the 
molecules which make up the gas. If its light waves, 
propagated through the ether, impinge on a quantity of the 
same gas, the molecules of that gas will be set into vibratory 
motion ; but that motion, being distributed over a large 
number of molecules, will be so weakened in amplitude as to 
V 



338 



MODERN CHEMISTRY 



be imperceptible. Hence, if the yellow light emitted from 
incandescent sodium gas falls upon a sufficient quantity of 
the same gas, which is not at so high a temperature as to 
emit visible light, it will be almost completely absorbed. 
The sodium light will 
not pass through the 
sodium gas. By this 
simple fact the chemi- 
cal analysis of the sun 
and stars is made 
possible. For exam- 
ple, the sun is a vast 
ball of white - hot 
matter. It is sending 
forth a mighty torrent 
of light of all con- 
ceivable frequencies. 
Among these vibra- 
tions are some which 
agree in period with 
those given out by 
incandescent sodium. 
But the sun is sur- 
rounded by an atmos- 
phere of sodium gas, 
cooler than the white- 
hot matter below it. 
Hence these vibrations will not be transmitted through the 
sodium vapour, but will be quenched in it in the way pre- 
viously explained. It is for this reason that we see in the 
yellow part of solar spectrum two dark lines very close 
together. These lines are absolutely identical in position 
with the pair of bright yellow sodium lines visible when 
glowing sodium vapour is viewed through a spectroscope. 
And thus we know that sodium is in the sun. In the same 
way, by comparing the dark lines seen in the solar and stellar 
spectra with the bright lines produced by incandescent gases, 
it has been discovered that most of the elements which orcur 
on the earth also occur on the sun and in the stars. 




Fig. 74. — The Sun, showing how the dark 
sodium lines are formed in its spectrum^ 
The dazzlingly white-hot interior sends out 
light of all wave lengths. Those falling 
upon the layer of relatively cool sodium 
vapour surrounding it all pass through 
except those which sodium vapour absorbs.- 
And hence the sun's spectrum contains two 
dark bands which correspond to sodium* 




Fig. 75. — The Nebula in Andromeda. 
(From a photograph taken at the Yerkes Observatory.) 



Orange y&llov 



Solar 
S/icctrum 



7/zcfifjo fiolct 




Fig. 70. — Spectra of Sun and some heated Metals. 

The spectrum at the top is diagrammatic only, and serves to show that the sun's 
spectrum consists of dark lines on a coloured background. The actual solar spectrum 
contains an infinitely greater number of lines than are represented here. 
(Illustration from Philip's " The Romance of Chemistry," p„207. Seeley & Co., 1910.) 

Face page 338, 



FIRE, FLAME, AND SPECTRAL ANALYSIS 339 

Indeed, we have spectroscopic evidence that in the sun 
and in many nebulae strange elements occur which are com- 
pletely unknown upon the earth. Such elements are 
coronium, nebulium, asterium, and some others. Helium 
was in this way first discovered in the sun some years before 
it was found upon the table. 

By noticing the displacements of the spectral lines to the 
left or to the right it is possible to tell the rate of motion of 
the stars either towards or from us. And wonderful results 
have thus been brought to light. Where once was thought 
to be rest has now been shown to be terrific motion. Many 
suns are rushing away from us at the rate of a million miles 
a day, and others are rushing towards us at an even greater 
speed. Vast flames of glowing gas, rushing upwards at the 
rate of 400 or 500 miles a second to the height of hundreds of 
thousands of miles have been shown to wheel about the sun's 
disc. The spectroscope has also told us of stupendous 
masses of glowing gas, so gigantic that the mind can scarcely 
grasp their extent, which lie buried in the depths of space. 
The spectroscope proves, alsc? s that many of the distant stars 
really consist of pairs of suns revolving rapidly about each 
other with a period which can be exactly determined by 
observing the periodic changes in their spectra. 

Thus the spectroscope has thrown a flood of light upon the 
mysteries of the depths of space, the problems of the infinitely 
great. But it has illuminated equally vividly the mysteries 
of the atomic universe, the problems of the infinitely little. 
For the absorption spectra of the different compounds 
allow us to actually measure the rates at which their 
molecules vibrate, and sometimes even allow us to decide 
the probable way that the atoms are arranged in the 
molecule. At the same time the fixity of the rays in the 
spectrum of each gas, their enormous number within the 
limits of the visible spectrum, and the greater number that 
exist beyond, show us how wonderfully regular the internal 
motions of the atoms and molecules are, and at the same 
time how extremely complex a structure these tiny objects 
have. The banded spectra, those beautiful lines of coloured 
light, introduce us to a world below the atom, and tell 



340 MODERN CHEMISTRY 

us that here also, as well as in the universe of worlds 
and stars about us, is a theatre in which vast forces and 
terrific motions play their part. To the keen-eyed chemist 
and physicist they are "an undecyphered hieroglyphic 
written upon the portals of the atomic world, in which are 
concealed the key to some of the deepest mysteries of 
creation. There they extend before us, as stretched the 
wide Atlantic before the gaze of Columbus, mocking, taunt- 
ing, and murmuring strange riddles, which no man yet 
has been able to solve." * Just as Columbus's long philo- 
sophic meditation led him to the fixed belief of the exist- 
ence of a yet untrodden world beyond that waste of Atlantic 
waters, so also did these mysterious bands and lines of light 
lead physicists and chemists to believe in the existence of 
a world beneath the atom long before the discovery of 
radium made this a certainty. They have opened up a new 
world which men are only now beginning to enter and 
explore. 

* Sir William Crookes, 



INDEX 



Abdul Hamid, 220 

Absolute Zero, Milton's land of, 

145 
Absorption spectra, 336 et seq., 

338 et seq. 
Acetylene, Soot from, 223 
Acheson's factories, 223 
Adelsberg, Cave of, 252, 256, 261 
Africa, South, Diamond fields of, 

212 et seq. 
Agate, 267 
Agriculture, Use of nitrogen 

manures in, 195 et seq. 
Agrigentum, 292 
Air (see under Atmosphere) 
Air, Liquid, 141 et seq., 148, 

182 
Alaghez, Volcano of, Sulphur on, 

296 
Albania, 252 
Aleutian Islands, 89 
Alexandria, 288 
America, Hot springs in, 85 
Amethyst, 272 
Ammonia, 202 
Ammonium Sulphate, use as 

manure, 195 
Amundsen, Capt., 158 
Animal Heat, 165 
Animal World, Insignificance of, 

in scheme of Nature, 186 
Antoinette, Marie, 220 
Aosta, Graphite beds of, 223 
Apatite, 317 

Aqueous Vapour, 96, 104, 134 
Arcturus, 47, 48 
Argo, Nebula in, 43 



Aristarchus, 162 
Aristotle, 127 
Armenia, Sulphur in, 296 
Arrhenius, 33, 34, 36, 42, 45, 46, 
54, 85, 130, 154, 
156, 162, 198, 203, 
246 
on the atmosphere, 
130, 154, 156, 198, 
202, 246 
on atmospheric car- 
bon dioxide, 246 
on the circulation of 
nitrogen in Nature, 
203 
on evolution of ele- 
ments, 42 
on fixation of at- 
mospheric nitrogen, 
198 
on height of atmo- 
sphere, 130 
on interior of earth, 

33 
on life in the Uni- 
verse, 54 
on meteorites, 34 
on planetary atmos- 
pheres, 162 
,, on stellar tempera- 
tures, 45, 46 
Arsenic, 209 

Asymmetric carbon atoms, 28 
Atherstone, Dr., 214 
Atmosphere, 126 et seq., 247 
,, Antiquity of, 133 

„ Carbon dioxide in, 

133, I34» 136, I54> 
247 et seq. 



341 



342 



INDEX 



Atmosphere, Changes in, 153 et 
seq., 286 
„ Composition of , 1 3 3 , 

I35» 140 
Complexity of, 141 
Dust in, 139 
Fixation of nitro- 
gen of, 196 et seq. 
Future of, 132, 157 
Height of, 130 
Invisibility of, 128 
Origin of, 132 
Origin of oxygen in, 

156 et seq. 

Ozone in, 135, 137, 

187 

Planetary, 160 et 

seq. 

Pressure of, 118, 

130. 131 

Primeval, Constitu- 
tion of, 153, 285 
et seq. 
Protection of, 

against cold, 129 
Protection of, 
against meteor- 
ites, 130 
Superstitions re- 
garding, 126 
temperature of, In- 
fluence of carbon 
dioxide on, 247 
Water in, 134, 135 
Weight of, 128 
Atomic Dissociation, 42, 115 
(see also under Radium, 
Evolution of elements,' etc.) 
Atomic Theory of Dalton, 15 

„ of the Greeks, 

11 et seq. 

„ of the Indians, 

140 

Atomic Universe, Comparison 

with stellar, 78 et seq. 

„ Weights, 32, 33, 124 

Atoms, 4, 11 et seq., 17 et seq., 25 

etseq.,69, 124, 232, 235 



Atoms, Asymmetric, 28 

Complexity of, 336 
„ Evolution of, 38 et seq. 
„ Motions of, 19, 20 et seq., 
59 et seq., 108, 123, 
232, 233, 336, 339 
„ Shape of, 25 et seq., 124 
„ Size of, 18 et seq., 25, 124, 
172 
„ Structure of, 124 
,, Visibility of, 25 

Weight of, 32, 33, 124 
Attila, 128 

Aurora Borealis, 132, 138, 139, 

187 
Avogadro, 16 et seq. 



Babil, 288 

Babylon, 288 

Bacteria, Effect of great cold on, 

150 

Ball, Sir Robert, 47 
Balloons, 117 
Bamboos, Silica in, 279 
Barral & Bixio's Balloon As- 
cents, 118 
Basalt, Weathering of, 284 
Beans, Fixation of nitrogen by, 

197 
Becquerel, 45 
Beni-Hassan, 288 
Berne Museum, 275 
Beryl, 281 
Beta Rays, 8, 115 
Birkeland-Eyde's process for fix- 
ing nitrogen, 199 et seq. 
Birs Nimroud, 288 
Bixio, 118 
Blacklead Pencils, 222 
Bleaching by sulphur dioxide, 

305 

Blood, Absorption of oxygen by, 
166 et seq. 
„ Blue and green, of insects, 
168 



■ 






INDEX 



343 



Boiler, Explosion of, no 

„ Scale, 251 
Bone, Phosphorus in, 315 
Bottomless Pit, mammoth cave, 

257 
Bottomley, researches on nitro- 
gen-fixing organisms, 197 
Braithwaite, " Ode to the sea," 

83 
Brand, Discovery of phosphorus 

by, 308 
Bricks, Manufacture of, 288 
Brown & Morris on cellulose, 

230 
Brownian Movement, 22 et seq. 
Bryant & May's Match Factory, 

314 et seq. 
Biidoshegg, Sulphur cave at, 297 
Bunsen Burners, 329 
Byron on the ocean, 82 



Calcium Bicarbonate, 251 

„ Carbide, Absorption of 

nitrogen by, 201 
„ Carbonate, 36, 67, 68, 

207, 241, 250, 251 
„ Cyanamide, 202 
„ Phosphate, 316 
Camphor 231 
Canopus, 47 
CapeUa, 47 
Carbon, 26, 206 et seq. 

,, atom, Shape of, 26 et 
seq. 
„ clouds in the sun, 208 
„ Chemical forces of, 228 
„ circulation in Nature, 
244. 245 
„ Compounds, Complexity 

of, 230 
„ in man, Quantity of, 
207 
„ Inertness of, 229 
,, Melting point of, 209 
, , Self -combination of , 2 2 8, 
229 et seq. 



Carbon, Volatilisation of, 208, 

209, 228 

Carbon Dioxide, 133, 134, 136, 

154-157, 166, 

167, 170, 217, 

227, 234-262 

„ absorption by 

ocean, 246 

absorption by 

plants, 249 
absorption by 
rocks (wea- 
thering), 241, 
285 et seq. 
„ amounts stored 

in rocks, 154, 
241, 242, 286 
„ Atmospheric, 

133, 134, 136, 
154, 155, 234. 
240, 241, 
242 
„ Decomposition 

of, by sun- 
light, 156, 
227, 228, 
242, 243 
„ Evolution of, 

from animals, 
166, 240, 241 
„ Evolution of, 

from the 

earth, 236 et 
seq., 238, 239 
„ Evolution of, 

from vol- 

canoes, 238 
et seq., 241 
,, Formation of 

coal from, 227 
., from combus- 

tion, 217, 234, 
241 
„ in mineral 

waters, 235 
„ in primeval at- 

mosphere, 

154, 242 



344 



INDEX 



Carbon Dioxide, influence on cli- 
mate, 247 
,, Molecule of, 235 

„ Poisonous ef- 

fects of, 235, 
238 et seq. 
„ Preparation of, 

235. 2 36 
w presence in cel- 

lars and sub- 
terranean 
places, 236, 

237» 239 
„ Properties of, 

236 
„ withdrawal 

from atmo- 
sphere, 241, 
242, 245 et 
seq., 285 
Carbonic Acid, 250 
Carboniferous Epoch, 250 
Carinthia, 252 
Caripe, Cave of, 255 
Carniola, 252, 253 et seq. 
Carpenter, Dr., 100 
Cathode Rays, 8 
Carbide, Calcium, Absorption of 

nitrogen by, 201 
Caves, 252 et seq., 296 

„ Collapse of, causing 
earthquakes and lakes, 
260, 261 
„ Sulphur, 297 
„ Volcanic, 296 et seq. 
Cellulose, 230 
Cephalonia, Fissues in limestone 

of, 256 
Ceria, 331 

Chalk, 36, 67, 68, 207, 241, 250, 
251, 262, 263 
Change, Incessant, of Nature, 
11, 31, 205 
Charcoal, 232, Absorption of 
gases by, 224 
„ Decolourising proper- 
ties of, 224 
„ Structure of, 224 



Challenger, on research, 332 

Chamberlin, on carbon dioxide 
in the air, 154, 242, 245 

Charles, Balloon ascent of, 118 

Charles II., 308 

Chemical changes at high tem- 
peratures 
and pres- 
sures, 46, 

47, 48, 49 
„ Complexity of, 

60 et seq. 
„ Heat and 

light pro- 
duced in, 
59 et seq., 

325 

„ in stars and 

nebulae, 37 

et seq., 44 

et seq., 48, 

5i 

„ Wonders of, 

55 et seq., 

333 

Chemical Forces, 57 et seq., 64 
et seq., 228 

Chemistry, Limited scope of, 49 
„ Science of, 9 

Chili Saltpetre, Use of, as man- 
ure, 196 

China Clay, 281, 287 

China Grass, 331 

Chinese Ink, 224 

Chlorocruorin, 168 

Chlorophyll, 242 

Circulation of matter in the 

Universe, 1, 2, 91, 195, 244, 

245, 3i8, 319-323 

Civilisation, Modern, Influence of 
carbon on, 206 

Clark, 280, 318 

Clay, 281, 285, 287, 289, 290 

Climate, Influence of carbon 
dioxide on, 248 et seq. 

Clouds, Formation of, 135 

Clover, Fixation of nitrogen by, 

197 






INDEX 



345 



Coal, 225 et seq. 

„ Combustion of, 234 
„ Story of, 228 
„ Swamps, 90, 225, 226 
Cold, Influence of, on properties 
of substances, 121, 146, 
150 
„ Influence of, on seeds and 

bacteria, 150 
„ of space, 120, 122, 129, 
146, 151 
Colesburg, Discovery of dia- 
monds near, 214 
Coleridge, 256, 261 
Colloidal solution of metals, 24 
Combustion, Nature of, 325 
Constant Proportions, Law of, 15 
Constitutional Formulae, 71, 72 
Copper and Sulphur, Combina- 
tion of, 56 
Coprolites, 318 
Corpuscles, 7, 37, 44 et seq., 50, 

5i 
Cortez, Sulphur for campaign of, 

297 

Cosmic Dust, 134 

Courrieres, Mining disaster at, 

169, 173 

Coxwell and Glaisher's Balloon 

Ascents, 118 
Crawford, 294 
Creatine, 202 
Creighton, Bishop, 237 
Croce-Spinelli, 119 
Ciookes, Sir W,, on Diamonds, 
208, 209, 217 
M on Melting and 

Boiling Point 
of Carbon, 209 
„ on Nitrogen-fix- 

ing problem, 
193 et seq., 
196, 198 
Crust of Earth, Changes in, by 
evolution of 
elements, 41 
„ ,. Chemical nature 
of, 36 



Crust of Earth, Corrosion of, by 
water, 95, 284 
et seq. 
, „ History of, 85 

Weathering of, 
241, 283 etseq. 
Cullinan Diamond, 221 
Cyanamide, Calcium, 202 



d'Albe, Fournier, 79 

Dalmatia, 252 

Dalton's Atomic Theory, 15 et 

seq. 
Damant, Lieut., 177 
Davidson, John, 269 
Davy, experiments on diamonds, 

219 
De Rerum Natura, Lucretius', 

11 etseq., 262 
Death Gulch, 236 
Death, Valley of, in Java, 236 
Democritus, 11, 14 
Denudation, 284 et seq. 
Deserts, 267, 269 
Dewar, 119, 122, 137, 141, 143 
Diamonds, 208-222 

Combustibility of 

the, 217 

Crystallisation of the, 

212 

Explosion of the, 212, 

217 

Fields of India, 212 

et seq. 

Fields of South 

Africa, 212 et seq. 

Hardness of the, 216 

Historic, Stories of, 

219 et seq. 
How formed in 
Nature, 211 
Internal strains in 

the, 212, 217 
Manufacture of the 
artificial, 209 et 
seq. 



346 



INDEX 



Diamond Mines, 212 et seq. 

"Pipes" of South 
Africa, 212 
„ Strange life-story of 

a, 216 
Value of the, 209 
Diatoms, 279 
Distribution of the Elements, 

* 33. 36 

Draeger, oxygen-breathing ap- 
paratus, 174 
Dragon Tree, 95 
Dumas, 112 
Duncan, Prof., 230 
Dust, Atmospheric, 138, 139 
„ Cosmical, 34, 138 



Earth, Our, 31 et seq. 
„ Changes of the, 40 
„ Corrosion of surface of, 

by water, 95 
„ Crust of, 36, 87, 281 
„ Early history of, 84 
„ Electrical charge of the, 
187 
„ Energies of, derived from 

sun's radiation, 244, 

245 
„ Future of, 40, 159 
„ Interior of the, 33, 88 
„ Internal heat of, 89, 90 
„ Maintenance of present 

temperature of, 86 
„ Penetration of water into 

the, 88, 89, 90 

„ Secular cooling of the, 86 

„ Size of the, 9, 47 

Earthquakes, Cause of, 88, 89, 

261, 262 

Echo River, of Mammoth Cave, 

258 
Egyptians, Ancient, Manufac- 
ture of glass and pottery by, 
288, 289 
Electric furnaces, 199, 310 
Electrical Forces, 58 
Electrolysis of Water, in 



Electrons, 7, 37, 39, 43, 50, 51, 
60, 79, 172 
„ how they produce 

light, 60 
Elements, 9, 31 et seq. 

Atomic weights of, 32 

Distribution of, 33, 

36, 40 

Evolution of, 37 et 

seq., 41, 50 
lighter than hydrogen, 
38, 39. 42 
Stellar evolution of, 

4*. 50 

Symbols of, 32 
Elgar, 127 
Elkin, 48 

Elliott, Scott, 92, 94 
Epicurus, 11 
Equations, Chemical, 68 
Erdmann, 137 

Ertrofu, Sulphur deposits on, 294 
Estremadura, Phosphate de- 
posits of, 317 
Ether, The, 4, 5, 6, 7, 8, 129, 324 
Etna, Volcanic caves of, 296 
Evolution of matter and ele- 
ments (see under Elements, 
Matter) 
Ewing, Prof., 185 
Exploded Mines, Use of oxygen 

in, 172 et seq. 
Exploding Worlds, Le Bon on, 

114 
Explosion, Boiler, no 

,, of hydrogen and oxy- 
gen, 119, 121 
„ of potassium chlorate 

at St. Helens, 180 
,, on stars, 48, 114 
Explosive, Use of liquid air as an, 
* 148 

Eyde's nitrogen-fixing factory, 

199 



Faust, 64 
Felspar, 282 



INDEX 



347 



Fertility of Soils, 195, 316, 319 
Fire, 324 et seq. 
Flames, 324 et seq. 

„ Complexity of, 60, 326 

et seq., 333 
„ Luminosity of, 328 

Structure of, 326, 327 
et seq. 
Fleuss, oxygen-breathing ap- 
paratus, 172-177 
Flint, 267, 270 et seq. 

„ Implements of prehistoric 
men, 270 
Fog, 136 
Food, Artificial, manufacture 

from the atmosphere, 202 
Forces, Chemical, 57 et seq., 64 
et seq., 228 
Electrical, 58 et seq. 
„ Gigantic, on stars, 48 
Formulae, Chemical, 66 et seq. 
„ „ Interpreta- 

tion of, 71 
Fossa della Palomba, 296 
Fouquet, Nicolas, 220 
Fournier d'Albe, 79 
Francis I., Loss of diamonds of, 

218 
Franke, Prof., process for fixing 

nitrogen, 201, 203 
Freeh, Prof., 249 
French Revolution, Loss of dia- 
monds in, 219, 220 
Freund, 14 

Furnace, Electric, 199 et seq., 

310 

G 

Galenstock, 273 
Galton, Francis, 5 
Ganges, 95 

Gas Mantles, 330 et seq. 
Gases, Absorption of, by char- 
coal, 224 
Gay Lussac's Balloon Ascents, 

118 
Geikie, 47 
Gems, Hepworth on, 208 



Germany, 331 

Gessner, Conrad, 222 

Geysers, 276 

Girgenti, Sulphur mines of, 292, 

293 
Glaciers, 102 
Glaisher & Coxwell's Balloon 

Ascents, 118, 130 
Glass, 288 

„ Quartz, 275 
Godlewski, 249 
Gold, 268 

„ Colloidal solutions of, 24 
Goldstein, on formation of ozone, 

188 
Gore, J. E., 43, 48 
Gorin's Dome, in Mammoth 

Cave, 257 
Granite, 36 

„ Weathering of, 284 et seq. 
Graphite, 222, 223 
Grasses, Silica in, 279 
Gravitation, 7 
Greece, 252 

Greeks, Atomic theory of an- 
cient, n et seq. 
Greenland, Cliffs of, destruction 
by ice, 10 1 
„ Metallic iron blocks 
found in, 35 
Grew, 88 
Griffin, 304 

Grotto del Cane, 237, 238 
Grottos (see Caves) 
Guacharos, 255 
Guadiana, 252 
Guanidine, 202 
Guano, 316 

Gundstrom's Safety Matches, 

313 
Guttannen, Village of, 273 
Guye, Prof., 203 



H 



Haemocyanin, 168 
Haemoglobin, 166, 167, 168 



348 



INDEX 



Hamlet on the indestructibility 

of matter, 2 
Hampson, 142 
Hamstead Mining Disaster, Use 

of oxygen in, 173 
Hannay and Hogarth, 210 
Hardness of Water, 251 
Heat, Animal, due to combus- 
tion, 165 
Heat and Light, Evolution of, 
in chemical 
changes, 59 
et seq. 
„ „ radiated by sun, 

244 
„ „ radiated into 

space, 53, 244 
Helium, 39, 42, 51, 120, 133, 

137 
„ Liquefaction of, 120 
Hellriegel, discovery of nitrogen- 
fixing organisms, 197 
Heraclitus, 205 
Herculaneum, Ink on MS. found 

at, 229 
Hiltner and Nobbe, 198 
Hogarth, 210 
Hogbom, 154, 241 
Holmes, Oliver Wendel, 165, 242 
Hope Diamond, Story of, 220 
Hopetown, Discovery of dia- 
monds near, 213 
Hot Springs, 85, 92, 279 
Howard, 304 
Hutchin's discovery of Mammoth 

Cave, 259 
Hydrogen, 107-125 

atoms, Size of, 123 

„ Structure of, 

125 

Atmospheric, 117, 137 

and exploding worlds, 

114 

Jballoons, 117 

Celestial, 112 et seq., 

116 
evolution of elemen- 
tary, 38 et seq. 



Hydrogen, Explosion of, in a 

boiler, in 

„ Explosion of, with 

oxygen, 119, 121 

flames on the sun, 113 

from volcanoes, 117 

gas, Structure of, 123 

et seq. 
in meteorites, 116 
in water, 96 et seq., 
116 
Liquefaction of, 119, 
120 
liquid, Properties of, 

119 et seq., 122 
Preparation of, 107 et 

seq. 
Properties of, 119 
Prout's hypothesis 

and, 112 
Stellar evolution of, 

114 et seq. 
sulphide, 302 et seq. 
(see under Sulphuretted hy- 
drogen) 



Ice, 86, 98-102 
„ Formation of, 98 
„ lightness of, Cosmical con- 
sequences of, 100 
„ Mineral, 86 
,, Structure of, 102 
Iceland, 238, 276, 307 

„ Caves of (volcanic), 297 
„ Geyser of, 276 
„ Volcanic eruptions of, 
238, 307 
Incandescent Gas Mantles, 330 
India, Diamond fields of, 213 
Indian Ink, 229 
Indigo, 231 
Ink, 229 

Innocents Abroad, 300 
Ionic Theory, 68 
Iron, Action of, on steam, no 




INDEX 



349 



Iron, Atomic weight of, 32 
„ Blocks of, at Disco, 35 
„ in earth's interior, 33 et 

seq. 
„ Sulphide of, 15 

Istria, 252 

Iwogasima, Sulphur on, 294 



Jacobs, 213 

Japan, Cause of earthquakes in, 

89 
„ Sulphur deposits of, 294 
Jamchand, the diamond mer- 
chant, 219 
Java, Death valley of, 236 

„ Sulphur lake in, 296 
Jessup, A. C. and A. E., 39, 40 
Jonkoping safety matches, 313 
Jupiter, 87, 163 



Kaolin, 281 
Kaufmann, 8 

Kelvin, Lord (Sir William Thom- 
son), 18 
Kieselguhr, 279 
Kimberley Diamond Mines, 214, 

215 
Kingsley, 227 
Kipling's " Sea Cables," 84 
Kipping, Prof., 29, 74 
Koehne, 157 

Koh-i-noor Diamond, 220 
Krafft, 308 
Krypton, 133, 138 
" Kubla Khan," 256 



Laacher See, 237 

Lake of Zirknitz, 260 

Lakes formed by collapse of 

caverns, 260, 261 
Laibach, Cave of, 252 
Lamballe, Princesse de, 220 



Lambert, the diver, 176 
Lambert, the fat man, 90 
Lampblack, 223 
Lanarto, Meteor from, 116 
Landerer, 266 
Langley, 113 
Larmor, 7 

Lavoisier, experiments on dia- 
monds, 218 
Law of constant proportions, 15 
„ of multiple proportions, 15 
Le Bel, 28, 74 
Le Bon, 8, 114, 147 
Leguminous Plants, Fixation of 

nitrogen by, 197 
Liebig, 245, 316 

Life (see also under Living Mat- 
ter, Protoplasm), 19, 20, 
54, 64, 85, 86, 90, 91, 
92, 93, 150, 151, 165, 166, 
186, 197, 207, 229, 242, 
245, 279, 280, 301 
„ Arrhenius' theory of its 

circulation in space, 151 
„ compared to fire, 165 
„ Earliest forms of, 91 et seq. 
„ in hot springs, 85, 92, 279 
,, Maintenance of, by sun's 

rays, 86, 245 
„ Minimum size of germs of, 
19, 20 
,, Origin of, 92 et seq., 151 et 

seq. 

„ Universal, 54, 93 et seq., 

151 et seq., 186 

Light, 8, 34, 53, 60, 61, 62, 139, 

244, 324, 325 

Cause of, in chemical 

changes, 60, 325 
Radiation of, by the sun, 
244 
Radiation of, into space 

53. *39 

Radiation pressure of, 34, 

139 

Velocity of, 8, 324 
Vibrations of, 60, 61, 62, 
33£ 



350 



INDEX 



Lightning, Combination of nitro- 
gen by, 192, 194 
Limestone caves, 252 et seq. 

„ Chemical nature of, 
36 
„ Solution of, 53 
Linde, Apparatus for liquefying 
air, 142, 143, 183 
„ Apparatus for manufac- 
turing oxygen, 183 
Liquefaction of Gases, 120, 141, 
142, 143, 182 
Liquid Air (see Air) 
Liquid Hydrogen (see Hydrogen) 
Living Germs, Minimum size of, 
19, 20 
Living Matter (see also Life, Pro- 
toplasm), 19, 
20, 54, 64, 85, 
86, 90, 91, 92, 
93, 150, 151, 
165, 166, 186, 
197, 207, 229, 
242, 245, 279, 
280, 301 
„ Atomic events in, 

64 
„ Carbon in, 207 

„ Ceaseless changes 

of, 166 
,, Chemical evolu- 

tion of, 280, 
301 
Chemical opera- 
tions performed 
by, 197, 229, 
242 et seq. 
„ Effect of great 

cold on, 150 et 
seq. 
„ Elements in, 207, 

280 
„ Fixation of nitro- 

gen by, 197 
„ in hot springs, 

85. 92, 279 
„ Minimum size of 

germs of, 19, 20 



Living Matter, Molecular struc- 
ture of, 19, 20 
„ Rapidity of 

atomic events 
in, 64 
„ Silica in, 279 et 

seq. 
,, Slow combustion 

going on in, 165 
et seq. 
„ Water in, 90 

„ Wonderful chemi- 

cal actions 

carried out by, 
197, 229, 242 
Lockyer, Sir Norman, 41, 45 
Lodge, Sir Oliver, 3, 5, 129, 172 
Louis XVI. , 220 
Lowell on Mars, 163 
Lower Greensand, 317 
Lucretius on atoms, n et seq., 
„ on Earthquakes, 262 

Lungs, Function of, 167 



Macquer, 218 

Maelstrom, in Mammoth Cave, 

Maintenon, Madame de, 220 
Mammoth Cave, 256 et seq. 
Mammoth, Frozen corpses of, 

151 

Mammoth Springs, Silica de- 
posits of, 278 

Man, Weight of various ele- 
ments in, 207 

Mangrove Swamps, 227 

Manures, 195, 316, 317 
„ Nitrogen, 195 
„ Phosphorus, 316, 317 

Marble, 36, 67, 68, 207 

Marignac, 112 

Mark Antony, 272 

Mark Twain, 300 

Mars, 87, 105, 162 

Mass, 8 
„ Variation of, with velocity, 

8 



INDEX 



35i 



Matches, Manufacture of, 310 et 

Mattan Diamond, 220 [seq. 

Matter, 8, 20, 195, 243, 245, 

318-323 

„ Atomic structure of, 4, 

5, 6, 7, 8, 20 et seq. 
„ Circulation of, in the 
universe, 1, 2, n, 195, 
243. 245, 318-323 
„ Indestructibility of, 2, 3, 

8 
„ movement through ether, 

4 
„ Theories of, 6-8 
Maxwell, 17 
Mayer, on the storage of sun's 

rays by plants, 244 
Mc Arthur's poem " Silence," 152 
McKendrick, Prof., 150 
Mendeldef, 78, 79, 223 
Mercury, 163 

Merlack, Mining disaster at, 173 
Mesopotamia, 287 et seq. 
Metasilicic Acid, 278 
Meteorites, 34, 116, 130, 139 

„ Chemical nature of, 

34 
„ Formation of, 34 
„ Hydrogen in, 116 

„ Lanarto, 116 

„ Velocities of, 130, 

139 

Meyer, Victor, 46 

Mica, 281 

Microscope, The Ultra-, 22 et 

seq. 

Microscopic Vision, Limit of, 23 

Milky Way, 80 

Milo, Sulphur caves at, 297 

Milton, 88, 145 

Mine Explosions, Use of oxygen 
in, 172 et seq. 

Mississippi, 25, 226 

Moissan, Manufacture of artifi- 
cial diamonds by, 209, 210 

Molecular weights, 67 

Molecules, 17, 18, 20, 25, 59, 62, 
70, 77, 123, 172, 333 



Molecules, Collision of, 59, 62 et 
seq., 77, 333 
„ hydrogen, Structure 

of, 123 

„ Internal motions of, 

30, 73, 232, 233 

„ oxygen, Structure 

and magnitude of, 

172 

„ Possibility of seeing, 

25 

„ Shape of, 25 et seq. 

„ Size of, 18, 25, 70, 
123, 172 

„ Speeds of, 20 et seq. 

„ Structure of, 70 et 
seq., 123 

„ world, Motion in, 21 
et seq., 25, 30, 59, 
62, 108, 140, 232, 

233 
Montano, Francisco, 297 
Montespan, Madame de, 220 
Montezuma, 297 
Moon, Absence of air and water 
from, 90, 161 
„ Absence of life on, 152 
„ Rocks of, 266 
,, Sulphur on, 298 
„ Volcanoes of, 298, 299 
Morions, 272, 273, 274 
Morris, Sir Lewis, 54, 65, 81 
Morris and Brown on starch, 230 
Mountains, Lowering of boiling 
point on, 105 
„ Pressure of atmos- 

phere on, 130, 131 
Moyors Bay, 295 
Muir, 14 

Multiple Proportions, Law of, 15 
Muscovite, 281 



Nagarka, 125 

Nature, Complexity of, 63 



352 



INDEX 



Nebulae, Chemical changes go- 
ing on in, 44, 45 
„ Evolution of elements 

in, 42 et seq., 44 
„ Hydrogen in, 113 
„ Size of, 43 
„ Unknown elements in, 
38, 41, et seq. 
Negroes in Kimberley diamond 

mines, 215 
Neptune, 87, 163 
New Red Sandstone, 267 
New Zealand, Cause of earth- 
quakes in, 89 
, , Hot Springs of, 85 , 

277, 278 
„ Siliceous deposits 

in, 277, 278 
Newcomb, Simon, 44, 47, 53 
Newton, 11 
Niagara Falls, Electric factories 

at, 223 
Niekirk, Schalk van, 213 
Nitragin, 198 

Nitrates, Manufacture of, 199 et 

seq. 
„ Use of, as manure, 195 
Nitrides, 192, 193 
Nitrogen, 189-205 

Atmospheric, 133, 189 

atom, Story of a, 

204 

Chemical inertness of, 

191, 192, 203 
Choking properties of, 
191 
Circulation of, in 
Nature, 195, 203, 
204 
Combustion of, with 
other elements, 192 
Combination with 
oxygen, 192, 198, 
199 et seq. 
Energies of, 192, 203 
Fixation of, by arti- 
ficial means, 199 et 
seq. 



Nitrogen, Fixation of, by na- 
tural means, 194 et 
seq. 
„ Fixation of, by plants, 
197 
in manures, 193, 194 
necessary for fertility 

of soils, 194 
Optical activity of, 29 
Planetary atmospheres 

of, 191 
Preparation of, 189 
Properties of, 190 
in stars and nebulae, 
190, 191 
Nobbe and Hiltner, 198 
Nonius, 272 

Notodden, Nitrogen-fixing fac- 
tory at, 199 



Oak Trees, Water evaporated 

by, 94. 95 
Ocean, 82-85, 89, 90, 98, 99, 105, 

246 
„ Absorption of, by earth's 

crust, 88, 89, 90 
„ Absorption of carbon 
dioxide by, 246 
Age of, 82, 83 
,, Amount of water in, 83 
Bottom of, 83, 84 
Depth of, 83, 89, 98 
,, Freezing of, 99 et seq. 
„ Future of, 89, 90, 159 
„ Origin of, 84 et seq. 
„ Pressure at bottom of, 83, 
89, 98 
,, primeval, Temperature 
of, 105 
Olivine, 281 
Olszewski, 119 
Onnes, Prof., 120, 121 
Opals, 267, 271, 272 
Optical Activity, 28 et seq., 74 
O'Reilly, 214 
Orloff Diamond, 220 



INDEX 



353 



Orthoclase Felspar, 282 
Ostwald, Prof. W., 286 
Oxidation of Blood, 166 et seq. 
Oxygen, 165-188 

„ Animal life dependent 

upon, 168 et seq. 
,, Animal respiration in, 

166, et seq. 
„ Atmospheric, origin of, 
156, 170 
„ breathing apparatus, 

172 et seq. 
„ Combustion of bodies 

in, 170 et seq. 
„ Discovery of, 178 
„ in the sun, 186 
„ in stars, 186 
„ in water, 96 et seq. 
„ in earth's crust, 185, 
186 
„ Largest preparation of, 

on record, 181 
„ Life-saving use of, 173 
„ Liquid, 171 
„ Magnetic properties of, 
171 
„ Manufacture from li- 
quid air, 182 
„ molecules, 172 
„ planets, 171, 186 
„ Preparation of , 179 
„ Properties of, 169 
„ Restorative effect of, 

178 et seq. 
„ stars, 186 
„ vast quantities in Na- 
ture, 185 
Oxyhemoglobin, 167 
Oxy-hydrogen blowpipe flame, 
Ozone, 134, 137, 187, 188 [275 
„ Atmospheric, 134,137,187 
„ Explosive properties of, 
188 
„ as an energy- trap, 188 



Paracelsus, 107 

1 



Pasteur, 28, 74 

Peas, Fixation of nitrogen by, 

Pencils, Blacklead, 222 [197 

Perseus, New star in, 9, 115 

Peru, Guano from, 316 

Pettenkofer, 207 

Phipson, researches on atmos 

phere, 154, 157 
Phosphates as manure, 317 
Phosphorescence, 309, 324 
Phosphorus, 308-323 

„ atom, Story of a, 

3i9 
„ Circulation of, in 

Nature, 318-323 
„ Discovery of, 308 

„ Fertility produced 

by presence of, in 

soil, 316 
„ in living matter, 315 

„ in the soil, 316 

„ Inflammability of, 

309 
„ Luminosity of, 308 

et seq. 
„ Manufacture of, 310 

„ Manure, 317 

„ Matches, 310-313 

ti Poisonous proper- 

ties of, 311, 312 
Phossy Jaw, 311 
Pitt or Regent Diamond, 219 
Planetary Atmospheres, 160 et 

seq. 
Planetary Collisions, 8, 9, 77 
Planina, Cave of, 252, 253 
Planets, Dark, 77, 78, 152 

,, Ozone, 188 
Plants, Absorption of carbon 
/lioxide by, 249, 250 
„ Amount of water in, 91 
„ Silica in, 279 
Pliny, Death of, 306 
Poik, the subterranean river, 
252, 253 
Polar Regions, 102, 158 
Polarisation, Rotation of plane 
of, 28, 74 



354 



INDEX 






Polishing Earth, 279 

Pope, 29, 74 

Popocatapetl, Sulphur in, 297, 

Porcelain, 290 

Potasi, 130 

Potassium Chlorate, Explosion 

of, 180 
Pottery, 287 et seq. 
Premier Diamond Mine, 221 
Prentice, Exploration of Mael- 
strom by, 258 
Pressure, Influence of, on boiling 
water, 104 
,, Influence of, on freez- 
ing point of water, 
101 
Pressures, at bottom of sea, 83, 
89, 98 
„ at centre of earth, 47 

,, in stars, 47, 48 

„ in sun, 47 

Priestley, discovery of oxygen 

by, 178 
Protons, 39 

Protoplasm (see under Life, Liv- 
ing Matter), 59, 
90, 280, 301 
„ Changes in, 59 

„ Chemical evolution 

of, 280, 301 
„ Water in, 90 et seq. 

Prout's Hypothesis, 112 
Punch, 208 

Puzzuoli, Sulphur deposits at, 
295 



Quartz, 267, 268, 269, 275 
,, fibres, 276 
„ glass, 275 



Radiant Energy of sun, 244 

„ of sun poured 

into space, 53 



Radiant Energy, Storage of, by 
vegetation, 
244 
Radiation, Absorption of, 335 
„ Pressure of, 34, 139, 

151 

., pressure of, Spread of 
life through uni- 
verse by, 151 
Radioactive Elements, 50 
Radiolaria, 279 
Radium, 31, 51 et seq., 86, 157 
Ramie Grass, 331 
Ramsay, Sir William, 37, 39 
Red Phosphorus, 313 
Reden, Mining disaster at, 173 
Regent or Pitt Diamond, 219 
Research, Value of, 332 
Respiration, Chemical changes 

in, 166 
Revolution, French, 219, 220 
Reynolds, Prof. Osborne, theory 

of matter, 6 
Rigel, Light emitted by, 48 
Rivers, Subterranean, 252 
Rock, Chemical nature of, 36, 
280, 281 et seq. 
,, Crystal, 267, 272 et seq. 
„ Metallic iron particles in 

volcanic, 36 
„ Oxygen in, 185 
,, Structure of, 281 
,, Weathering of, 241, 285 
et seq. 
Roman Empire, Manufacture of 

glass in, 288 
Rontgen, 45 

Rotomahana, Fairy Lake of. 

277 
Rutherford, 39, 51 



Safety Matches, 313 

Saleeby, on intra-atomic energy, 

Saltpetre, Chili, 195 






INDEX 



355 



Sand, 267, 269, 270, 285, 287 

Sandstone, 267 

Sarcosine, 202 

Saturn, 87, 163 

Schalk van Niekerk, 213 

Scheele, 310 

Schenk's scarlet phosphorus, 314 

Schmidl, Dr., exploration of 
caves, 253 et seq. 

Sea (see under Ocean) 

Sea-water, Freezing of, 98 et seq. 

Seeds, Effect of great cold on, 150 

Senses, basis of all knowledge, 5 

Serpentine, 287 

Sesostris, 288 

Severn Tunnel, Saving of, by 
oxygen apparatus, 175 

Sevil, 119 

Shakespeare on the indestructi- 
bility of matter, 2 

Shenstone, 30 

Sicily, Sulphur mines of, 291 

Side Saddle Pit in Mammoth 
Cave, 257 

Sidon, 288 

Siedentopf, 25 

Silica, 267, 276, 278 

„ Deposits of, 277, 278 

,, in grasses and straw, 279 

„ in living matter, 279 

Silicates, Constitution of, 280 

Silicon, 29, 32, 265 

„ Atomic weight of, 32 
,, Optical activity of, 29 

Silicic Acid, 106, 276, 278, 280, 
et seq. 

Sillard, 215 

Silver, Colloidal solutions of, 24 

Skaptar Jokul, Eruption of, 238 

Slags, Phosphorus in, 317 

Smith's Point Lighthouse, 302 

Smoke Quartz, 272 

Snow Crystals, 102 

Snowdon, 284 

Soddy, 39 

Sftfium in sun, 338 

H Nitrate, use as manure, 
195 



Sodium, Vapour, radiations of, 
Soil, Fertility of, 195, 316 [338 
Sombrero, Phosphate from, 317 
Sommatino, Sulphur mine of, 

293 
South Africa, Diamond fields of, 

213 
Space, Coldness of, 120, 122, 129 
Spectra, 336 et seq. 
Spectroscope, 336 et seq. 
Spencer, Herbert, on the Uni- 
verse, 52 
J Spitzbergen, Destruction of cliffs 
in, 101 
Springs, Hot, 85, 92, 279 
St. Helens, Explosion of chlorate 

at, 180 
St. Michael, Volcanic caves of, 

296 

Stalactites and Stalagmites, 254, 

262, 263 

Star of the South, 220 

Stars, 8, 9, 41, 45, 47, 48, 62, 77, 

334. 338 
,, Chemical analysis of, 334 

et seq., 338 
„ Chemical changes in, 45 

et seq. 
,, Collisions of, 8, 9, 62, 77 

Evolution of, 41 et seq., 45 
,, Forces on, 48 et seq. 

Light emitted by, 47, 48 
New, 9 

Pressures in, 47, 48 
,, Size of, 47, 48 
Streams of, 62 
Temperatures of, 45 
Stas, 112 
Steam, 103, no (see Aqueous 

Vapour) 
Stellar Universe compared with 

Atomic, 78 et seq. 
Stereo-Chemistry, 25 et seq., 74 
Stevenson, 248 

Stoney, Dr. Johnstone, on Size 
of Atoms, 19, 60, 62 
„ Dr. Johnstone, on plane- 
tary atmospheres, 161 



356 



INDEX 



Straw, Silica in, 279 

Streeter, 208, 218 

Student life in England and 

Germany, 332 
Subterranean Rivers, 252 et seq. 
Sugars, 230, 231 
Sulphide of Copper, 56 
Sulphides of Iron, 15 
Sulphur, 291-307 

,, Bacteria, 300 

,, caves, 297 

„ Combination of, with 

copper, 56 
,, dioxide, 305 
„ Extraction of, 292-294 
,, Flowers of, 292 
,, Formation of, in vol- 
canic districts, 291, 
295, 296, 298 
in living matter, 301 
in Vesuvius, 299 
Mines, 291 et seq. 
Occurrence of, 291-298 
Optical activity of, 29 
Plastic, 302 
Properties of, 301 
Sulphuretted hydrogen, 302-305 
„ Evolution of, from 

ground, 302 
, , Poisonous effects of , 

302 et seq. 

,, Preparation of, 305 

Sulphuric Acid, 70, 72, 73, 76, 

107, 108, 307 

„ action on metals, 

107, 108 

„ Constitution of 

molecule of, 

70, 72, 73, 76 

Sulzer, 274 

Sun, 9, 47, 93, 113, 164, 207, 208, 
228, 244, 245, 338 
„ Atmosphere of, 164 
„ Carbon clouds in, 208, 228 
„ Chemical analysis of, 338 
„ Energy radiated by, 244 
„ Explosions on, 48 
„ Flames on, 9, 113 



Sun, parent of all earthly ener- 
gies, 244, 245 
„ Size of, 9, 47, 93, 207 
Suns, Burnt out, 120 
Surt-shellier Cave, 297 
Sweden, Safety matches of, 313 
Symbols, Chemical, 66 



Tait, 98 

Tamarugal, Nitrate beds of, 196 
Tampo, Lake of, 277 
Tartrates, optically active, 28 et 

seq. 

Tavornia, Andreas, 220 

Temperatures, High, effect on 

properties of 

substances, 105, 

106 

„ High, Discoveries 

at, 46 

„ High, Change of 

properties at, 

106, 121 

„ Highest possible, 

46 

„ Low, Change of 

properties at, 

11 45, 46, 106, 120, 

121, 122, 146, 

158 
„ Lowest tempera- 

ture recorded 
on earth, 158 
Stellar, 45, 46 
Teneriffe, 296, 299 
Tennyson, 11, 82, 90 
Thomson, Sir William (Lord 

Kelvin), 18 
Thomson, Prof. J. J., 27, 37, 38, 
40, 41, 44, 51, 79, 125 
Thoria, 330 
Tillmann, 49 

Tin, Optical activity of, 29 
Tissandier, 119 
Tunbridge, 317 
Trees, 94, 95 
„ Age of, 94 



INDEX 



357 



Trees, Water evaporated by, 94, 

95 
Tripler, 142, 148 
Tripoli, 279 

Trowbridge on limits of atmos- 
phere, 131 
Tuscarora Deep, 89 
Tyre, 288 



Ultramicroscope, 22 et seq. 
United States, 85, 279, 288, 332 
„ Glass manufac- 

ture in, 288 
„ Hot springs in, 

85, 279 
„ Student life in, 

332 
Universe, Amount of matter in, 9 
Atomic, compared 
with stellar, 78 et 
seq. 
Complexity of, 9, 232, 
233 
Cosmical dust in, 139 
Evolution of, 37 et 

seq., 51 et seq. 
Life in, 54, 93 et seq., 

151 et seq. 
Lucretius on, 1 1 et seq. 
Motion in stellar, 339 
stellar, Collisions in, 
62 
Theories of, 6 et seq. 
Unz, the subterranean river, 252 
Uranus, 163 
Urea, 202 



Vacuum Jacketed Flasks, 144, 

*45 
Valency, 26, 27 

Valley of Death, in Java, 236 

Van't Horf, 28, 74 

Vegetation, Decomposition of 

carbon dioxide by, 

243 I 



Vegetation, Evaporation of 
water by, 94, 95 
Venus, 87, 162 
Venus's Flower Basket, 279 
Vesuvius, Crater of, 299 

„ Eruption of, in a.d* 79, 

305 
„ Evolution of carbon 
dioxide by, 237 
Victor Meyer on chemical dis- 
coveries at high tempera- 
tures, 46 
Vision, Limit of microscopic, 23 
Vitruvius, 127 
Volcanoes, 237, 238, 305, 307 

„ Evolution of carbon 

dioxide gas by, 237, 

238, 3°7 

M Evolution of sulphur 

dioxide gas by, 

305, 307 

Volcanic Rocks, 36, 280, 318, 319 

„ Analysis of, 280 

et seq. 

„ Metallic iron in, 

36 

„ Phosphorus in, 

318, 319 

Von Buch on Teneriffe, 296 



W 



Wagstadt, 261 

Wallace, 146 

Wallsend, 208 

Water, 82-106, 134, 135, 136, 251 
„ Absorption of, by 

minerals, 88 et seq. 
,, action on metals, no, 1 1 1 
„ Atmospheric, 134 
,, Boiling point of, 103 et 
seq. 
,, Chemical nature of, 96 
„ Circulation of, in Nature, 

94, 95 
„ Climatic influence of, 96, 

I34» 136 



358 



INDEX 



Water Effect of high tempera- 
tures on properties of, 
105 
,, Evolution of, by plants, 

94 
„ Freezing of, 98, 100, 101 
„ Hardness of, 251 
,, in living matter, 90 et 
seq., 94 
in plants, 91, 94 
,, Incompressibility of, 98 
,, Planetary, 87 et seq. 
,, Properties of, 98 et seq., 

105 
,, Temperature of, maxi- 
mum density, 99 
vapour, 96, 104, 134, 135 
Water Glass, 278 
Weathering of Rocks, 241, 285 

et seq. 
Wells, 221 



! Welsbach, 330 
I Whetham, 7, 41 
; Williamson, 130 
Wislicenus, 27, 74 



Xenolite, 281 



Yellowstone Park, 278, 279 
Young, 113 



Zinc, Action of acids on, 107, 108 
,, Action of hot water on, no 
Zirknitz, Lake of, 260 
Zsigmondy on the ultra- 
microscope, 24 



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Vol. III. Ammonia Soda (In Press.) 

Vol. IV. Electrolytic Methods (In Press.) 

Technical Chemists' Handbook i2mo, leather, *4 00 

Technical Methods of Chemical Analysis. Trans, by 

C. A. Keane. In collaboration with the corps of 
specialists. 

Vol. I. In two parts 8vo, *i5 00 

Vol. II. In two parts 8vo, *i8 00 

Vol. III. In two parts 8vo, *i8 00 

The set (3 vols.) complete *5o 00 

Technical Gas Analysis 8vo, *4 50 

Luquer, L. M. Minerals in Rock Sections, 8vo, *i 50 

MacBride, J. D. A Handbook of Practical Shipbuilding, 

i2mo, fabrikoid 2 00 

Macewen, H. A. Food Inspection 8vo, *2 50 

Mackenzie, N. F. Notes on Irrigation Works 8vo, *2 50 

Mackie, J. How to Make a Woolen Mill Pay 8vo, *2 25 

Maguire, Wm. R. Domestic Sanitary Drainage and Plumbing 

8vo, 4 00 

Malcolm, C. W. Textbook on Graphic Statics 8vo, *3 00 

Malcolm, H. W. SuDmarine Telegraph Cable (In Press.) 

Mallet, A. Compound Engines. Trans, by R. R. Buel. 
(Science Series No. 10.) i6mo, 



28 D. VAN NOSTRAND COMPANY/ S SHORT-TITLE CATALOG 

Mansfield, A. N. Electro-magnets. (Science Series No. 64) 

i6mo, 50 
Marks, E. C. R. Construction of Cranes and Lifting Machinery 

I2H10, *2 00 

Construction and Working of Pumps i2mo, 

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Mechanical Engineering Materials . i2mo, *i 50 

Marks, G. C. Hydraulic Power Engineering 8vo, 4 50 

Inventions, Patents and Designs nmo, *i 00 

Marlow, T. G. Drying Machinery and Practice 8vo, *5 00 

Marsh, C. F. Concise Treatise on Reinforced Concrete . . . 8vo, *2 50 
Marsh, C. F. Reinforced Concrete Compression Member 

Diagram Mounted on Cloth Boards *i 50 

Marsh, C. F., and Dunn, W. Manual of Reinforced Concrete 

and Concrete Block Construction. .. .i6mo, fabrikoid, 

(In Press.) 
Marshall, W.J., and Sankey, H. R. Gas Engines. (Westminster 

Series.) 8vo, *2 00 

Martin, G. Triumphs and Wonders of Modern Chemistry. 

8vo, *2 00 

Modern Chemistry and Its Wonders 8vo, *2 00 

Martin, N. Properties and Design of Reinforced Concrete, 

i2mo, *2 50 

Martin, W. D. Hints to Engineers i2mo, 1 50 

Massie, W. W., and Underhill, C. R. Wireless Telegraphy and 

Telephony nmo, *i 00 

Mathot, R. E. Internal Combustion Engines 8vo, *4 00 

Maurice, W. Electric Blasting Apparatus and Explosives . .8vo, *3 50 

Shot Firer's Guide 8vo, *i 50 

Maxwell, F. Sulphitation in White Sugar Manufacture. i2mo, 375 
Maxwell, J. C. Matter and Motion. (Science Series No. 36.) 

i6mo, 50 
Maxwell, W. H., and Brown, J. T. Encyclopedia of Municipal 

and Sanitary Engineering 4to, *io 00 

Mayer, A. M. Lecture Notes on Physics 8vo, 2 00 

Mayer, C, and Slippy, J. C. Telephone Line Construction . 8vo, *3 00 

McCullough, E. Practical Surveying ^, i2mo, *2 00 

Engineering Work in Cities and Towns 8vo, *3 00 

Reinforced Concrete i2mo, *i 50 

McCullough, R. S. Mechanical Theory of Heat. . 8vo, 3 50 



D. VAN NOSTRAND COMPANY'S SHORT-TITLE CATALOG 20, 

McGibbon, W. C. Indicator Diagrams for Marine Engineers, 

8vo, *3 50 

Marine Engineers' Drawing Book oblong 4to, *2 50 

Marine Engineers' Pocketbook i2mo, leather, *4 00 

Mcintosh, J. G. Technology of Sugar 8vo, *7 25 

Industrial Alcohol 8vo, *4 25 

Manufacture of Varnishes and Kindred Industries. 

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Vol. I. Oil Crushing, Refining and Boiling 

Vol. II. Varnish Materials and Oil Varnish Making *6 25 

Vol. III. Spirit Varnishes and Materials *7 25 

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Business 8vo, (In Press.) 

McKillop, M., and McKillop, D. A. Efficiency Methods. 

i2mo, 1 50 
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Boilers *2 50 

McMaster, J. B. Bridge and Tunnel Centres. (Science Series 

No. 20.) i6mo, o 50 

McMechen, F. L. Tests for Ores, Minerals and Metals. . . i2mo, *i 00 

McPherson, J. A. Water-works Distribution 8vo, 2 50 

Meade, A. Modern Gas Works Practice 8vo, *8 50 

Meade, R. K. Design and Equipment of Small Chemical 

Laboratories 8vo, 

Melick, C. W. Dairy Laboratory Guide i2mo, *i 25 

Mensch, L. J. Reinforced Concrete Pocket Book.i6mo, leather *4 00 
"Mentor." Self-Instruction for Students in Gas Supply, 

i2mo, 2 50 

Advanced Self -Instruction for Students in Gas Supply, 

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Merck, E. Chemical Reagents: Their Purity and Tests. 

Trans, by H. E. Schenck 8vo, 1 00 

Merivale, J. H. Notes and Formulae for Mining Students, 

i2mo, 
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Mertens, Colonel. Tactics and Technique in River Crossings. 

Translated by Major Walter Krueger 8vo, 

Mierzinski, S. Waterproofing of Fabrics. Trans, by A. Morris 

and H. Robson 8vo, 

Miessner, B. F. Radiodynamics i2mo, 

Miller, G. A. Determinants. (Science Series No. 105.). . i6mo, 

I Miller, W. J. Historical Geology iamo, 

Mills, C. N. Elementary Mechanics for Engineers i2mo, 

Milroy, M. E. W. Home Lace -making i2mo, 



I 


50 


2 


00 


2 


50 


*3 

*2 


00 
00 


*2 
*I 
*I 


00 
00 

00 



JO D. VAN NOSTRAND COMPANY'S SHORT-TITLE CATALOG 

Mitchell, C. A. Mineral and Aerated Waters 8vo, *3 oo 

— and Prideaux, R. M. Fibres Used in Textile and 

Allied Industries 8vo, *4 25 

Mitchell, C. F. and G. A. Building Construction and Draw- 
ing i2mo 

Elementary Course, *i 50 
Advanced Course, *2 50 
Monckton, C. C. F. Radiotelegraphy. (Westminster Series.) 

8vo, *2 00 
Monteverde, R. D. Vest Pocket Glossary of English-Spanish, 

Spanish-English Technical Terms 64mo, leather, *i 00 

Montgomery, J. H. Electric Wiring Specifications. .. .i6mo, *i 00 
Moore, E. C. S. New Tables for the Complete Solution of 

Ganguillet and Kutter's Formula 8vo, *5 00 

Moore, Harold. Liquid Fuel for Internal Combustion Engines, 

8vo, 5 00 
Morecroft, J. H., and Hehre, F. W. Short Course in Electrical 

Testing 8vo, *i 50 

Morgan, A. P. Wireless Telegraph Apparatus for Amateurs, 

i2mo, *i 50 
Morgan, C. E. Practical Seamanship for the Merchant 

Marine i2mo, f abrikoid {In Press.) 

Moses, A. J. The Characters of Crystals 8vo, *2 00 

and Parsons, C. L. Elements of Mineralogy 8vo, * 3 50 

Moss, S. A. Elements of Gas Engine Design. (Science 

Series No. 121) i6mo, o 50 

The Lay-out of Corliss Valve Gears. (Science Series 

No. 119.) i6mo, 

Mulford, A. C. Boundaries and Landmarks i2mo, 

Mullin, J. P. Modern Moulding and Pattern-making. . . . i2mo, 
Munby, A. E. Chemistry and Physics of Building Materials. 

(Westminster Series.) 8vo, 

Murphy, J. G. Practical Mining i6mo, 

Murray, J. A. Soils and Manures. (Westminster Series. )8vo, 

Nasmith, J. The Student's Cotton Spinning 8vo, 

Recent Cotton Mill Construction i2mo, 

Neave, G. B., and Heilbron, I. M. Identification of Organic 

Compounds i2mo, *i 25 

Neilson, R. M. Aeroplane Patents 8vo, *2 00 






50 


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2 


00 


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50 



D. VAN NOSTRAND COMPANY'S SHORT-TITLE CATALOG 3 1 

lNerz, F. Searchlights. Trans, by C. Rodgers 8vo, *3 oo 

Neuberger, H., and Noalhat, H. Technology of Petroleum. 

Trans, by J. G. Mcintosh. 8vo, *io oo 

Newall, J. W. Drawing, Sizing and Cutting Bevel-gears. .8vo, 150 
Newbigin, M. I., and Flett, J. S. James Geikie, the Man 

and the Geologist. 8vo, 3 5° 

Newbiging, T. Handbook for Gas Engineers and Managers, 

8vo, *6 50 
Newell, F. H., and Drayer, C. E. Engineering as a Career. 

i2nio, cloth, *i 00 

paper, o 75 

Nicol, G. Ship Construction and Calculations 8vo, *5 00 

Nipher, F. E. Theory of Magnetic Measurements nmo, 1 00 

Nisbet, H. Grammar of Textile Design 8vo, 

Nolan, H. The Telescope. (Science Series No. 51.) i6mo, o 50 

Norie, J. W. Epitome of Navigation (2 Vols.) octavo, 15 00 

— A Complete Set of Nautical Tables with Explanations 

of Their Use octavo, 6 50 

North, H. B. Laboratory Experiments in General Chemistry 

i2mo, *i 00 

Nugent, E. Treatise on Optics i2mo, 1 50 

O'Connor, H. The Gas Engineer's Pocketbook. .. i2mo, leathei, 3 50 
Ohm, G. S., and Lockwood, T. D. Galvanic Circuit. Trans, by 

William Francis. (Science Series No. 102.). . . . i6mo, o 50 

Olsen, J. C. Textbook of Quantitative Chemical Analysis . . 8vo, *3 50 
Olsson, A. Motor Control, in Turret Turning and Gun Elevating. 

(U. S. Navy Electrical Series, No. 1.) . ...nmo, paper, *o 50 

Ormsby, M. T. M. Surveying i2mo, 2 50 

Oudin, M. A. Standard Polyphase Apparatus and Systems . .8vo, *3 00 

Owen, D. Recent Physical Research 8vo, 

Pakes, W. C. C, and Nankivell, A. T. The Science of Hygiene. 

8vo, *i 75 
Palaz, A. Industrial Photometry. Trans, by G. W. Patterson, 

J r 8vo, *4 00 

Pamely, C. Colliery Manager's Handbook 8vo, *io 00 

Parker, P. A. M. The Control of Water 8vo, *5 00 

Parr, G. D. A. Electrical Engineering Measuring Instruments. 

8vo, *3 50 
Parry, E. J. Chemistry of Essential Oils and Artificial Per- 
fumes I0 00 



32 D. VAN NOSTRAND COMPANY'S SHORT-TITLE CATALOG 

Parry, E J. Foods and Drugs. Two Volumes .8vo, 

Vol. I. Chemical and Microscopical Analysis of Food 
and Drugs ., 

Vol. II. Sale of Food and Drugs Acts 

and Coste, J. H. Chemistry of Pigments 8vo, 

Parry, L. Notes on Alloys 8vo, 

Metalliferous Wastes 8vo, 

Analysis of Ashes and Alloys 8vo, 

Parry, L. A. Risk and Dangers of Various Occupations. .8vo, 
Parshall, H. F., and Hobart, H. M. Armature Windings .... 4to, 

Electric Railway Engineering 4to, 

Parsons, J. L. Land Drainage 8vo, 

Parsons, S. J, Malleable Cast Iron 8vo, 

Partington, J. R. Higher Mathematics for Chemical Students 

i2mo, 

Textbook of Thermodynamics 8vo, 

Passmore, A. C. Technical Terms Used in Architecture . 8vo, 

Patchell, W. H. Electric Power in Mines 8vo, 

Faterson, G. W. L. Wiring Calculations i2mo, 

— — Electric Mine Signalling Installations. i2mo, 

Patterson, D. The Color Printing of Carpet Yarns 8vo, 

« Color Matching on Textiles 8vo, 

Textile Color Mixing 8vo, 

Paulding, C. P. Condensation of Steam in Covered and Bare 

Pipes 8vo, 

Transmission of Heat Through Cold-storage Insulation 

i2mo, 

Payne, D. W. Founders' Manual 8vo, 

Peckham, S. F. Solid Bitumens 8vo, 

Peddie, R. A. Engineering and Metallurgical Books. . . . i2mo, 

Peirce, B. System of Analytic Mechanics 4to, 

Linnear Associative Algebra 4to, 

Pendred, V. The Railway Locomotive. (Westminster Series.) 

8vo, 
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and Jaggers, E. M. Elementary Chemistry i2mo, 

Perrin, J. Atoms Svo, 

Perrine, F. A. C. Conductors for Electrical Distribution . . . 8vo, 



10 


00 


*4 

*6 

:;: 3 


25 
50 

50 


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;;; 4 


50 

25 


*7 


50 


10 


00 


*i 


50 


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50 


*2 


00 


>:< 4 


00 


*4 


25 


*4 


00 


*3 


00 


*i 


50 


"4 


25 



*2 00 



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00 


*4 


00 


*5 


00 


*i 


50 


10 


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3 


00 


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*4 25 
*4 25 


*4 25 



D. VAN NOSTF \NY\s SHORT-TITLE CATALOG 33 

Petit, G. White ■ ic White Paints 8vo, *2 50 

Petit, R. How to .eroplane. Trans, by T. O'B. 

Hubbard, teboer. 8vo, *i 50 

Pettit, Lieut. J. S. cesses. (Science Series No. 76.) 

i6mo, o 50 
Philbrick, P. H. Orders. (Science Series No. 88.) 

i6mo, 

Phillips, J. Go 8vo, *3 75 

Dangerous 8vo, . 3 50 

Phin, J. Seven jnce. i2mo, *i 25 

Pickworth, C. • :ator Handbook. Two Volumes 

i2mo, each, 1 50 

Logarithn rs nmo, boards, o 50 

The Slid i2mo, 2 50 

Pilcher, R. B ;-Jones, F. What Industry Owes 

to C nee i2mo, 1 50 

Plattner's Ma rpipe Analysis. Eighth Edition, re- 
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Plympton, G. »id Barometer. (Science Series.). i6mo, o 5a 

How t< Engineer. (Science Series No. 100.) 

i6mo, o 5a 

Van F- ble Book. (Science Series No. 104). 

i6mo, o 50 
Pochet, M. ijectors. Translated from the French. 

( No. 29.) i6mo, o 50 

Pocket Lc mr Places. (Science Series.) i6mo, 050 

leather, 1 00 

Polleyn, 3 and Finishings for Textile Fabrics . 8vo, *4 25 

Pope, F Chemistry i2mo, *2 50 

Pope, F. Practice of the Electric Telegraph.. . . 8vo, 1 50 

Popple^ Prevention of Smoke 8vo, *4 25 

St faterials 8vo, *2 ^50 

Porritt Chemistry of Rubber. (Chemical Mono- 

3-) i2mo, *i 00 

Porter ;opter Flying Machine i2mo, *i 50 

Potts, itry of the Rubber Industry. (Outlines of 

Chemistry.) 8vo, *2 50 

Pract iding of Oils, Tallow and Grease 8vo, *4 25 



34 D - VAN NOSTRAND C0MPA1 



TITLE CATALOG 



Pratt, K. Boiler Draught 

High Speed Steam Engines.. 

Pray, T., Jr. Twenty Years with the 

Steam Tables and Engine Consta 

Prelini, C. Earth and Rock Exca vatic 

Graphical Determination of Earth 

Tunneling 

Dredging. A Practical Treatise. . 

Prescott, A. B. Organic Analysis 

and Johnson, 0. C. Qualitative C 

and Sullivan, E. C. First Book in (, 

Prideaux, E. B. R. Problems in Physical 

Theory and Usib of Indicators 

Prince, G. T. Flow of Water 

Pullen, W. W. F. Application of Graphic M 

of Structures 

Injectors: Theory, Construction and 

Indicator Diagrams 

Engine Testing 

Putsch, A. Gas and Coal-dust Firing 

Pynchon, T. R. Introduction to Chemical Phj 



. . . i2mo, 
8vo, 

8vo, 

8vo, 

8vo, 

8vo, 

8vo, 

8vo, 

8vo, 

ysis . 8vo, 

lemistry 

i2mo, 

. 8vo, 

. . . 8vo, 

.i2mo, 

design 

r2mo, 

i2mo, 

.8vo, 

.8vo, 

vo, 



*2 OO 

2 50 

2 00 

*3 oo 

*2 00 

*3 oo 

*3 oo 

5 oo 

*3 50 

*i 50 

*2 00 

5 oo 

*2 OO 

*2 50 

*2 00 



-2 50 



*2 

*5 5o 

*3 00 

3 00 



Rafter, G. W. Mechanics of Ventilation. (Sci 

33-) 

Potable Water. (Science Series No. 103.). 

Treatment of Septic Sewage. (Science S 

and Baker, M. N. Sewage Disposal in the 

Raikes, H. P. Sewage Disposal Works 

Randau, P. Enamels and Enamelling 

Rankine, W. J. M. Applied Mechanics 

Civil Engineering. 

Machinery and Millwork 

— — The Steam-engine and Other Prime Movers 
and Bamber, E. F. A Mechanical Textbook 



o 50 
o 50 

o 50 

*6 00 
*4 00 
*7 2 5 

5 00 

6 50 

5 °° 
5 00 

3 50 



D. VAN NOSTRAND COMPANY'S SHORT-TITLE CATALOG 35 

Ransome, W. R. Freshman Mathematics i2mo, *i 35 

Raphael, F. C. Localization of Faults in Electric Light and 

Power Mains 8vo, *3 50 

Rasch, E. Electric Arc Phenomena. Trans, by K. Tornberg. 

8vo, *2 00 

Rathbone, R. L. B. Simple Jewellery 8vo, *2 00 

Rateau, A. Flow of Steam through Nozzles and Orifices. 

Trans, by H. B. Brydon 8vo, *i 5c 

Rausenberger, F. The Theory of the Recoil of Guns 8vo, *5 00 

Rautenstrauch, W. Notes on the Elements of Machine Design, 

8vo, boards, *i 50 
Rautenstrauch, W., and Williams, J. T. Machine Drafting and 
Empirical Design. 

Part I. Machine Drafting 8vo, *i 25 

Part II. Empirical Design (In Preparation.) 

Raymond, E. B. Alternating Current Engineering i2mo, *2 50 

Rayner, H. Silk Throwing and Waste Silk Spinning ... 8vo, 
Recipes for the Color, Paint, Varnish, Oil, Soap and Drysaltery 

Trades 8vo, *6 50 

Recipes for Flint Glass Making i2mo, *5 25 

Redfern, J. B., and Savin, J. Bells, Telephones. (Installa- 
tion Manuals Series.) i6mo, *o 50 

Redgrove, H. S. Experimental Mensuration i2mo, *i 25 

Redwood, B. Petroleum. (Science Series rio. 92.) . . . .i6mo, o 50 

Reed, S. Turbines Applied to Marine Propulsion *5 00 

Reed's Engineers' Handbook 8vo, *g 00 

Key to the Nineteenth Edition of Reed's Engineers' 

Handbook 8vo, *4 00 

Useful Hints to Sea-going Engineers i2mo, 3 00 

Reid, E. E. Introduction to Research in Organic Chemistry. 

(In Press.) 
Reid, H. A. Concrete and Reinforced Concrete Construction, 

8vo, *5 00 
Reinhardt, C. W. Lettering for Draftsmen, Engineers, and 

Students oblong 4to, boards, 1 00 

The Technic of Mechanical Drafting, .oblong 4to, boards, *i 00 



36 D. VAN NOSTRAND COMPANY^ SHORT-TITLE CATALOG 

Reiser, F. Hardening and Tempering of Steel. Trans, by A. 

Morris and H. Robson i2mo, 

Reiser, N. Faults in the Manufacture of Woolen Goods. Trans. 

by A. Morris and H. Robson 8vo, 

• Spinning and Weaving Calculations 8vo, 

Renwick, W. G. Marble and Marble Working 8vo, 

Reuleaux, F. The Constructor. Trans, by H. H. Suplee. .4to, 
Reuterdahl, A. Theory and Design of Reinforced Concrete 

Arches 8vo, 

Rey, J. Range of Electric Searchlight Projectors 8vo, 

Reynolds, 0., and Idell, F. E. Triple Expansion Engines. 

(Science Series No. 99.) i6mo, 

Rhead, G. F. Simple Structural Woodwork i2mo, 

Rhodes, H. J. Art of Lithography 8vo, 

Rice, J. M., and Johnson, W. W. A New Method of Obtaining 

the Differential of Functions i2mo, 

Richards, W. A. Forging of Iron and Steel nmo, 

Richards, W. A., and North, H. B. Manual of Cement Testing, 

i2mo, 
Richardson, J. The Modern Steam Engine 8vo, 

Richardson, S. S. Magnetism and Electricity i2mo, 

Rideal, S. Glue and Glue Testing 8vo, 

Riesenberg, F. The Men on Deck i2mo, 

Rimmer, E. J. Boiler Explosions, Collapses and Mishaps. 8vo, 

Rings, F. Concrete in Theory and Practice i2mo, 

Reinforced Concrete Bridges. ". 4to, 

Ripper, W. Course of Instruction in Machine Drawing. . . folio, 
Roberts, F. C. Figure of the Earth. (Science Series No. 79.) 

i6mo, o 50 
Roberts, J., Jr. Laboratory Work in Electrical Engineering 

8vo, *2 00 

Robertson, L. S. Water-tube Boilers 8vo, 2 00 

Robinson, J. B. Architectural Composition 8vo, *2 50 

Robinson, S. W. Practical Treatise on the Teeth of Wheels. 

(Science Series No. 24.) i6mo, o 50 

Railroad Economics. (Science Series No. 59.) i6mo, o 50 

Wrought Iron Bridge Members. (Science Series No. 

60.) i6mo, o 50 



*3 


00 


;:; 3 


00 


'6 


25 


5 


00 


*4 


00 


*2 


00 


*4 5o 





5o 


*i 


25 


6 


5o 





50 


1 


50 


*i 


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50 


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75 


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50 


;: 5 


00 


*6 


00 




D. VAN NOSTRAND COMPANY'S SHORT-TITLE CATALOG 37 

Robson, J. H. Machine Drawing and Sketching 8vo, 2 00 

Roebling, J. A. Long and Short Span Railway Bridges. . folio, 25 00 

Rogers, A. A Laboratory Guide of Industrial Chemistry . 8vo, 2 00 

Elements of Industrial Chemistry i2mo, 3 00 

Manual of Industrial Chemistry 8vo, *5 00 

Rogers, F. Magnetism of Iron Vessels. (Science Series No. 30.) 

i6mo, o 50 
Rohland, P. Colloidal and its Crystalloidal State of Mattel. 

Trans, by W. J. Britland and H. E. Potts . . _ . . i2mo, *i 25 

Rollinson, C. Alphabets '. oblong i2mo, *i 00 

Rose, J. The Pattern-makers' Assistant. 8vo, 2 50 

Key to Engines and Engine-running i2mo, 2 50 

Rose, T. K. The Precious Metals. (Westminster Series.) . .8vo, *2 00 

Rosenhain, W. Glass Manufacture. (Westminster Series.) . 8vo, *2 00 

Physical Metallurgy, An Introduction to. (Metallurgy 

Series.) 8vo, *3 50 

Roth, W. A. Physical Chemistry 8vo, *2 00 

Rowan, F.J. Practical Physics of the Modern Steam-boiler.8vo, *3 00 

and Idell, F. E. Boiler Incrustation and Corrosion. 

(Science Series ]Vo. 27.) i6mo, o 50 

Roxburgh, W. General Foundry Practice. (Westminster 

Series.) 8vo, *2 00 

Ruhmer, E. Wireless Telephony. Trans, by J. Erskine- 

Murray 8vo, *4 50 

Russell, A. Theory of Electric Cables and Networks 8vo, *3 00 

Rutley, F. Elements of Mineralogy i2mo, *i 25 

Sandeman, E. A. The Manufacture of Earthenware. .i2mo, 3 50 

Sanford, P. G. Nitro-explosives 8vo, *4 00 

Saunders, C. H. Handbook of Practical Mechanics i6mo, 1 00 

leather, 1 25 

Sayers, H. M. Brakes for Tram Cars 8vo, *i 25 

Scheele, C. W. Chemical Essays 8vo, *2 00 

Scheithauer, W. Shale Oils and Tars 8vo, *5 00 

Scherer, R. Casein. Trans, by C. Salter 8vo, *4 25 



♦6 


oo 


*2 


2S 


*I 


75 


*3 


oo 


i 


50 


*3 


oo 


*4 


So 


2 


50 


*6 


00 



38 D. VAN NOSTRAND COMPANY'S SHORT-TITLE CATALOG 

Schidrowitz, P. Rubber, Its Production and Industrial Uses, 

8vo, 

Schindler, K. Iron and Steel Construction Works i2mo, 

Schmall, C. N. First Course in Analytic Geometry, Plane and 

Solid i2mo, half leather, 

Schrneer, L. Flow of Water 8vo, 

Schumann, F. A Manual of Heating and Ventilation. 

i2mo, leather, 

Schwartz, E. H. L. Causal Geology 8vo, 

Schweizer, V. Distillation of Resins 8vo, 

Scott, W. W. Qualitative Analysis. A Laboratory Manual, 

New Edition 

Standard Methods of Chemical Analysis 8vo, 

Scribner, J. M. Engineers' and Mechanics' Companion. 

i6mo, leather, 1 50 
Scudder, H. Electrical Conductivity and Ionization Constants 

of Organic Compounds 8vo, *3 00 

Searle, A. B. MG&ern Brickmaking 8vo, *7 25 

Cement, Concrete and Bricks 8vo, *6 50 

Searle, G. M. " Sumners' Method." Condensed and Improved. 

(Science Series No. 124.) i6mo, o 50 

Seaton, A. E. Manual of Marine Engineering 8vo, 8 00 

Seaton, A. E., and Rounthwaite, H. M. Pocket-book of Marine 

Engineering i6tio, leather, 5 0o 

Seeligmann, T., Torrilhon, G. L., and Falconnet, H. India 
Rubber and Gutta Percha. Tra^s. by J. G. Mcintosh 

8vo, *7 25 
Seidell, A. Solubilities of Inorganic and Organic Substances, 

8vo, *3 00 

Seligman, R. Aluminum. (Metallurgy Series) (In Press.) 

Sellew, W. H. Steel Rails 4 to, *io 00 

Railway Maintenance Engineering i2mo, *2 50 

Senter, G. Outlines of Physical Chemistry i2mo, *2 00 

Textbook of Inorganic Chemistry i2mo, * 3 00 

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1 



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